diff --git a/content/base/src/nsDOMFile.cpp b/content/base/src/nsDOMFile.cpp
index 686255190c62..0de4253a84b9 100644
--- a/content/base/src/nsDOMFile.cpp
+++ b/content/base/src/nsDOMFile.cpp
@@ -17,7 +17,8 @@
 #include "nsIDocument.h"
 #include "nsIFileStreams.h"
 #include "nsIInputStream.h"
-#include "nsIIPCSerializable.h"
+#include "nsIIPCSerializableInputStream.h"
+#include "nsIIPCSerializableObsolete.h"
 #include "nsIMIMEService.h"
 #include "nsIPlatformCharset.h"
 #include "nsISeekableStream.h"
@@ -47,8 +48,9 @@ using namespace mozilla::dom;
 // stream is.  We do that by passing back this class instead.
 class DataOwnerAdapter MOZ_FINAL : public nsIInputStream,
                                    public nsISeekableStream,
-                                   public nsIIPCSerializable,
-                                   public nsIClassInfo
+                                   public nsIIPCSerializableObsolete,
+                                   public nsIClassInfo,
+                                   public nsIIPCSerializableInputStream
 {
   typedef nsDOMMemoryFile::DataOwner DataOwner;
 public:
@@ -65,16 +67,18 @@ public:
 
   // These are optional. We use a conditional QI to keep them from being called
   // if the underlying stream doesn't QI to either interface.
-  NS_FORWARD_NSIIPCSERIALIZABLE(mSerializable->)
+  NS_FORWARD_NSIIPCSERIALIZABLEOBSOLETE(mSerializableObsolete->)
   NS_FORWARD_NSICLASSINFO(mClassInfo->)
+  NS_FORWARD_NSIIPCSERIALIZABLEINPUTSTREAM(mSerializableInputStream->)
 
 private:
   DataOwnerAdapter(DataOwner* aDataOwner,
                    nsIInputStream* aStream)
     : mDataOwner(aDataOwner), mStream(aStream),
       mSeekableStream(do_QueryInterface(aStream)),
-      mSerializable(do_QueryInterface(aStream)),
-      mClassInfo(do_QueryInterface(aStream))
+      mSerializableObsolete(do_QueryInterface(aStream)),
+      mClassInfo(do_QueryInterface(aStream)),
+      mSerializableInputStream(do_QueryInterface(aStream))
   {
     NS_ASSERTION(mSeekableStream, "Somebody gave us the wrong stream!");
   }
@@ -82,8 +86,9 @@ private:
   nsRefPtr<DataOwner> mDataOwner;
   nsCOMPtr<nsIInputStream> mStream;
   nsCOMPtr<nsISeekableStream> mSeekableStream;
-  nsCOMPtr<nsIIPCSerializable> mSerializable;
+  nsCOMPtr<nsIIPCSerializableObsolete> mSerializableObsolete;
   nsCOMPtr<nsIClassInfo> mClassInfo;
+  nsCOMPtr<nsIIPCSerializableInputStream> mSerializableInputStream;
 };
 
 NS_IMPL_THREADSAFE_ADDREF(DataOwnerAdapter)
@@ -92,8 +97,11 @@ NS_IMPL_THREADSAFE_RELEASE(DataOwnerAdapter)
 NS_INTERFACE_MAP_BEGIN(DataOwnerAdapter)
   NS_INTERFACE_MAP_ENTRY(nsIInputStream)
   NS_INTERFACE_MAP_ENTRY(nsISeekableStream)
-  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIIPCSerializable, mSerializable)
+  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIIPCSerializableObsolete,
+                                     mSerializableObsolete)
   NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIClassInfo, mClassInfo)
+  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIIPCSerializableInputStream,
+                                     mSerializableInputStream)
   NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIInputStream)
 NS_INTERFACE_MAP_END
 
diff --git a/docshell/base/SerializedLoadContext.h b/docshell/base/SerializedLoadContext.h
index c2ae9e8923ac..8fdd8c391bb3 100644
--- a/docshell/base/SerializedLoadContext.h
+++ b/docshell/base/SerializedLoadContext.h
@@ -9,7 +9,6 @@
 
 #include "base/basictypes.h"
 #include "IPC/IPCMessageUtils.h"
-#include "nsIIPCSerializable.h"
 #include "nsILoadContext.h"
 
 /*
diff --git a/dom/ipc/Blob.cpp b/dom/ipc/Blob.cpp
index a50044ecac4a..c1ac012574f4 100644
--- a/dom/ipc/Blob.cpp
+++ b/dom/ipc/Blob.cpp
@@ -10,13 +10,14 @@
 
 #include "nsIDOMFile.h"
 #include "nsIInputStream.h"
+#include "nsIIPCSerializableInputStream.h"
 #include "nsIRemoteBlob.h"
 #include "nsISeekableStream.h"
 
 #include "mozilla/Assertions.h"
 #include "mozilla/Monitor.h"
 #include "mozilla/unused.h"
-#include "mozilla/net/NeckoMessageUtils.h"
+#include "mozilla/ipc/InputStreamUtils.h"
 #include "nsDOMFile.h"
 #include "nsThreadUtils.h"
 
@@ -25,6 +26,7 @@
 
 using namespace mozilla::dom;
 using namespace mozilla::dom::ipc;
+using namespace mozilla::ipc;
 
 namespace {
 
@@ -227,10 +229,18 @@ private:
   }
 };
 
+NS_IMPL_THREADSAFE_ADDREF(RemoteInputStream)
+NS_IMPL_THREADSAFE_RELEASE(RemoteInputStream)
+
+NS_INTERFACE_MAP_BEGIN(RemoteInputStream)
+  NS_INTERFACE_MAP_ENTRY(nsIInputStream)
+  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsISeekableStream, IsSeekableStream())
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIInputStream)
+NS_INTERFACE_MAP_END
+
 template <ActorFlavorEnum ActorFlavor>
 class InputStreamActor : public BlobTraits<ActorFlavor>::StreamType
 {
-  typedef typename BlobTraits<ActorFlavor>::StreamType::InputStream InputStream;
   nsRefPtr<RemoteInputStream> mRemoteStream;
 
 public:
@@ -249,12 +259,17 @@ public:
 private:
   // This method is only called by the IPDL message machinery.
   virtual bool
-  Recv__delete__(const InputStream& aStream) MOZ_OVERRIDE
+  Recv__delete__(const InputStreamParams& aParams) MOZ_OVERRIDE
   {
     MOZ_ASSERT(NS_IsMainThread());
     MOZ_ASSERT(mRemoteStream);
 
-    mRemoteStream->SetStream(aStream);
+    nsCOMPtr<nsIInputStream> stream = DeserializeInputStream(aParams);
+    if (!stream) {
+      return false;
+    }
+
+    mRemoteStream->SetStream(stream);
     return true;
   }
 };
@@ -605,14 +620,10 @@ public:
   virtual void*
   GetPBlob() MOZ_OVERRIDE
   {
-    return static_cast<typename ActorType::BaseType*>(mActor);
+    return static_cast<typename ActorType::ProtocolType*>(mActor);
   }
 };
 
-} // namespace ipc
-} // namespace dom
-} // namespace mozilla
-
 template <ActorFlavorEnum ActorFlavor>
 Blob<ActorFlavor>::Blob(nsIDOMBlob* aBlob)
 : mBlob(aBlob), mRemoteBlob(nullptr), mOwnsBlob(true), mBlobIsFile(false)
@@ -740,7 +751,7 @@ Blob<ActorFlavor>::SetMysteryBlobInfo(const nsString& aName,
   ToConcreteBlob(mBlob)->SetLazyData(aName, aContentType, aLength);
 
   FileBlobConstructorParams params(aName, aContentType, aLength);
-  return BaseType::SendResolveMystery(params);
+  return ProtocolType::SendResolveMystery(params);
 }
 
 template <ActorFlavorEnum ActorFlavor>
@@ -759,7 +770,7 @@ Blob<ActorFlavor>::SetMysteryBlobInfo(const nsString& aContentType,
   ToConcreteBlob(mBlob)->SetLazyData(voidString, aContentType, aLength);
 
   NormalBlobConstructorParams params(aContentType, aLength);
-  return BaseType::SendResolveMystery(params);
+  return ProtocolType::SendResolveMystery(params);
 }
 
 template <ActorFlavorEnum ActorFlavor>
@@ -809,7 +820,7 @@ Blob<ActorFlavor>::NoteDyingRemoteBlob()
   // access a dangling pointer.
   mRemoteBlob = nullptr;
 
-  mozilla::unused << BaseType::Send__delete__(this);
+  mozilla::unused << ProtocolType::Send__delete__(this);
 }
 
 template <ActorFlavorEnum ActorFlavor>
@@ -868,9 +879,9 @@ Blob<ActorFlavor>::RecvResolveMystery(const ResolveMysteryParams& aParams)
   return true;
 }
 
-template <ActorFlavorEnum ActorFlavor>
+template <>
 bool
-Blob<ActorFlavor>::RecvPBlobStreamConstructor(StreamType* aActor)
+Blob<Parent>::RecvPBlobStreamConstructor(StreamType* aActor)
 {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT(mBlob);
@@ -880,7 +891,55 @@ Blob<ActorFlavor>::RecvPBlobStreamConstructor(StreamType* aActor)
   nsresult rv = mBlob->GetInternalStream(getter_AddRefs(stream));
   NS_ENSURE_SUCCESS(rv, false);
 
-  return aActor->Send__delete__(aActor, stream.get());
+  nsCOMPtr<nsIIPCSerializableInputStream> serializable =
+    do_QueryInterface(stream);
+  if (!serializable) {
+    MOZ_ASSERT(false, "Must be serializable!");
+    return false;
+  }
+
+  nsCOMPtr<nsIEventTarget> target =
+    do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID);
+  NS_ENSURE_TRUE(target, false);
+
+  nsRefPtr<BaseType::OpenStreamRunnable> runnable =
+    new BaseType::OpenStreamRunnable(this, aActor, stream, serializable,
+                                      target);
+
+  rv = target->Dispatch(runnable, NS_DISPATCH_NORMAL);
+  NS_ENSURE_SUCCESS(rv, false);
+
+  nsRevocableEventPtr<BaseType::OpenStreamRunnable>* arrayMember =
+    mOpenStreamRunnables.AppendElement();
+  *arrayMember = runnable;
+  return true;
+}
+
+template <>
+bool
+Blob<Child>::RecvPBlobStreamConstructor(StreamType* aActor)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mBlob);
+  MOZ_ASSERT(!mRemoteBlob);
+
+  nsCOMPtr<nsIInputStream> stream;
+  nsresult rv = mBlob->GetInternalStream(getter_AddRefs(stream));
+  NS_ENSURE_SUCCESS(rv, false);
+
+  nsCOMPtr<nsIIPCSerializableInputStream> serializable =
+    do_QueryInterface(stream);
+  if (!serializable) {
+    MOZ_ASSERT(false, "Must be serializable!");
+    return false;
+  }
+
+  InputStreamParams params;
+  serializable->Serialize(params);
+
+  MOZ_ASSERT(params.type() != InputStreamParams::T__None);
+
+  return aActor->Send__delete__(aActor, params);
 }
 
 template <ActorFlavorEnum ActorFlavor>
@@ -910,18 +969,127 @@ template <ActorFlavorEnum ActorFlavor>
 NS_IMPL_QUERY_INTERFACE_INHERITED1(RemoteBlob<ActorFlavor>, nsDOMFile,
                                                             nsIRemoteBlob)
 
-NS_IMPL_THREADSAFE_ADDREF(RemoteInputStream)
-NS_IMPL_THREADSAFE_RELEASE(RemoteInputStream)
+void
+BlobTraits<Parent>::BaseType::NoteRunnableCompleted(
+                    BlobTraits<Parent>::BaseType::OpenStreamRunnable* aRunnable)
+{
+  MOZ_ASSERT(NS_IsMainThread());
 
-NS_INTERFACE_MAP_BEGIN(RemoteInputStream)
-  NS_INTERFACE_MAP_ENTRY(nsIInputStream)
-  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsISeekableStream, IsSeekableStream())
-  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIInputStream)
-NS_INTERFACE_MAP_END
+  for (PRUint32 index = 0; index < mOpenStreamRunnables.Length(); index++) {
+    nsRevocableEventPtr<BaseType::OpenStreamRunnable>& runnable =
+      mOpenStreamRunnables[index];
 
-namespace mozilla {
-namespace dom {
-namespace ipc {
+    if (runnable.get() == aRunnable) {
+      runnable.Forget();
+      mOpenStreamRunnables.RemoveElementAt(index);
+      return;
+    }
+  }
+
+  MOZ_NOT_REACHED("Runnable not in our array!");
+}
+
+BlobTraits<Parent>::BaseType::
+OpenStreamRunnable::OpenStreamRunnable(
+                                   BlobTraits<Parent>::BaseType* aOwner,
+                                   BlobTraits<Parent>::StreamType* aActor,
+                                   nsIInputStream* aStream,
+                                   nsIIPCSerializableInputStream* aSerializable,
+                                   nsIEventTarget* aTarget)
+: mOwner(aOwner), mActor(aActor), mStream(aStream),
+  mSerializable(aSerializable), mTarget(aTarget), mRevoked(false),
+  mClosing(false)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aOwner);
+  MOZ_ASSERT(aActor);
+  MOZ_ASSERT(aStream);
+  MOZ_ASSERT(aSerializable);
+  MOZ_ASSERT(aTarget);
+}
+
+NS_IMETHODIMP
+BlobTraits<Parent>::BaseType::OpenStreamRunnable::Run()
+{
+  MOZ_ASSERT(mStream);
+
+  nsresult rv;
+
+  if (NS_IsMainThread()) {
+    MOZ_ASSERT(mTarget);
+    MOZ_ASSERT(!mClosing);
+
+    if (mRevoked) {
+      MOZ_ASSERT(!mOwner);
+      MOZ_ASSERT(!mActor);
+    }
+    else {
+      MOZ_ASSERT(mOwner);
+      MOZ_ASSERT(mActor);
+
+      nsCOMPtr<nsIIPCSerializableInputStream> serializable;
+      mSerializable.swap(serializable);
+
+      InputStreamParams params;
+      serializable->Serialize(params);
+
+      MOZ_ASSERT(params.type() != InputStreamParams::T__None);
+
+      unused << mActor->Send__delete__(mActor, params);
+
+      mOwner->NoteRunnableCompleted(this);
+
+#ifdef DEBUG
+      mOwner = nullptr;
+      mActor = nullptr;
+#endif
+    }
+
+    mClosing = true;
+
+    nsCOMPtr<nsIEventTarget> target;
+    mTarget.swap(target);
+
+    rv = target->Dispatch(this, NS_DISPATCH_NORMAL);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    return NS_OK;
+  }
+
+  if (!mClosing) {
+    // To force the stream open we call Available(). We don't actually care how
+    // much data is available.
+    PRUint64 available;
+    if (NS_FAILED(mStream->Available(&available))) {
+      NS_WARNING("Available failed on this stream!");
+    }
+
+    rv = NS_DispatchToMainThread(this, NS_DISPATCH_NORMAL);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    return NS_OK;
+  }
+
+  // Going to always release here.
+  nsCOMPtr<nsIInputStream> stream;
+  mStream.swap(stream);
+
+  rv = stream->Close();
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return NS_OK;
+}
+
+#ifdef DEBUG
+void
+BlobTraits<Parent>::BaseType::OpenStreamRunnable::Revoke()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  mOwner = nullptr;
+  mActor = nullptr;
+  mRevoked = true;
+}
+#endif
 
 // Explicit instantiation of both classes.
 template class Blob<Parent>;
diff --git a/dom/ipc/Blob.h b/dom/ipc/Blob.h
index 08e9f7419c8d..65f66e26b009 100644
--- a/dom/ipc/Blob.h
+++ b/dom/ipc/Blob.h
@@ -12,12 +12,16 @@
 #include "mozilla/dom/PBlobParent.h"
 #include "mozilla/dom/PBlobStreamChild.h"
 #include "mozilla/dom/PBlobStreamParent.h"
-#include "mozilla/dom/PContentChild.h"
-#include "mozilla/dom/PContentParent.h"
+#include "mozilla/dom/PContent.h"
+
 #include "nsAutoPtr.h"
 #include "nsCOMPtr.h"
+#include "nsTArray.h"
+#include "nsThreadUtils.h"
 
 class nsIDOMBlob;
+class nsIIPCSerializableInputStream;
+class nsIInputStream;
 
 namespace mozilla {
 namespace dom {
@@ -36,17 +40,92 @@ struct BlobTraits
 template <>
 struct BlobTraits<Parent>
 {
-  typedef mozilla::dom::PBlobParent BaseType;
+  typedef mozilla::dom::PBlobParent ProtocolType;
   typedef mozilla::dom::PBlobStreamParent StreamType;
-  typedef mozilla::dom::PContentParent ManagerType;
+
+  // BaseType on the parent side is a bit more complicated than for the child
+  // side. In the case of nsIInputStreams backed by files we need to ensure that
+  // the files are actually opened and closed on a background thread before we
+  // can send their file handles across to the child. The child process could
+  // crash during this process so we need to make sure we cancel the intended
+  // response in such a case. We do that by holding an array of
+  // nsRevocableEventPtr. If the child crashes then this actor will be destroyed
+  // and the nsRevocableEventPtr destructor will cancel any stream events that
+  // are currently in flight.
+  class BaseType : public ProtocolType
+  {
+  protected:
+    BaseType()
+    { }
+
+    virtual ~BaseType()
+    { }
+
+    // Each instance of this class will be dispatched to the network stream
+    // thread pool to run the first time where it will open the file input
+    // stream. It will then dispatch itself back to the main thread to send the
+    // child process its response (assuming that the child has not crashed). The
+    // runnable will then dispatch itself to the thread pool again in order to
+    // close the file input stream.
+    class OpenStreamRunnable : public nsRunnable
+    {
+      friend class nsRevocableEventPtr<OpenStreamRunnable>;
+    public:
+      NS_DECL_NSIRUNNABLE
+
+      OpenStreamRunnable(BaseType* aOwner, StreamType* aActor,
+                         nsIInputStream* aStream,
+                         nsIIPCSerializableInputStream* aSerializable,
+                         nsIEventTarget* aTarget);
+
+    private:
+#ifdef DEBUG
+      void
+      Revoke();
+#else
+      void
+      Revoke()
+      {
+        mRevoked = true;
+      }
+#endif
+
+      // Only safe to access these two pointers if mRevoked is false!
+      BaseType* mOwner;
+      StreamType* mActor;
+
+      nsCOMPtr<nsIInputStream> mStream;
+      nsCOMPtr<nsIIPCSerializableInputStream> mSerializable;
+      nsCOMPtr<nsIEventTarget> mTarget;
+
+      bool mRevoked;
+      bool mClosing;
+    };
+
+    friend class OpenStreamRunnable;
+
+    void
+    NoteRunnableCompleted(OpenStreamRunnable* aRunnable);
+
+    nsTArray<nsRevocableEventPtr<OpenStreamRunnable> > mOpenStreamRunnables;
+  };
 };
 
 template <>
 struct BlobTraits<Child>
 {
-  typedef mozilla::dom::PBlobChild BaseType;
+  typedef mozilla::dom::PBlobChild ProtocolType;
   typedef mozilla::dom::PBlobStreamChild StreamType;
-  typedef mozilla::dom::PContentChild ManagerType;
+
+  class BaseType : public ProtocolType
+  {
+  protected:
+    BaseType()
+    { }
+
+    virtual ~BaseType()
+    { }
+  };
 };
 
 template <ActorFlavorEnum>
@@ -58,9 +137,9 @@ class Blob : public BlobTraits<ActorFlavor>::BaseType
   friend class RemoteBlob<ActorFlavor>;
 
 public:
-  typedef typename BlobTraits<ActorFlavor>::BaseType BaseType;
+  typedef typename BlobTraits<ActorFlavor>::ProtocolType ProtocolType;
   typedef typename BlobTraits<ActorFlavor>::StreamType StreamType;
-  typedef typename BlobTraits<ActorFlavor>::ManagerType ManagerType;
+  typedef typename BlobTraits<ActorFlavor>::BaseType BaseType;
   typedef RemoteBlob<ActorFlavor> RemoteBlobType;
   typedef mozilla::ipc::IProtocolManager<
                       mozilla::ipc::RPCChannel::RPCListener>::ActorDestroyReason
diff --git a/dom/ipc/PBlobStream.ipdl b/dom/ipc/PBlobStream.ipdl
index 45be1cc0102f..aac11a1eabf2 100644
--- a/dom/ipc/PBlobStream.ipdl
+++ b/dom/ipc/PBlobStream.ipdl
@@ -3,10 +3,7 @@
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 include protocol PBlob;
-
-include "mozilla/net/NeckoMessageUtils.h";
-
-using IPC::InputStream;
+include IPCSerializableParams;
 
 namespace mozilla {
 namespace dom {
@@ -16,7 +13,7 @@ protocol PBlobStream
   manager PBlob;
 
 both:
-  __delete__(InputStream stream);
+  __delete__(InputStreamParams params);
 };
 
 } // namespace dom
diff --git a/dom/plugins/ipc/PPluginModule.ipdl b/dom/plugins/ipc/PPluginModule.ipdl
index f6c388ca08ef..5f2b837458ee 100644
--- a/dom/plugins/ipc/PPluginModule.ipdl
+++ b/dom/plugins/ipc/PPluginModule.ipdl
@@ -14,7 +14,6 @@ include "mozilla/dom/TabMessageUtils.h";
 
 using NPError;
 using NPNVariable;
-using base::FileDescriptor;
 using mozilla::dom::NativeThreadId;
 using mac_plugin_interposing::NSCursorInfo;
 using nsID;
diff --git a/dom/plugins/ipc/PluginModuleChild.cpp b/dom/plugins/ipc/PluginModuleChild.cpp
index 8ea5a3c106fd..52b027a77ce0 100644
--- a/dom/plugins/ipc/PluginModuleChild.cpp
+++ b/dom/plugins/ipc/PluginModuleChild.cpp
@@ -1850,10 +1850,10 @@ PluginModuleChild::AnswerNP_Initialize(const uint32_t& aFlags, NPError* _retval)
 #endif
 
 #ifdef MOZ_X11
-    // Send the parent a dup of our X socket, to act as a proxy
-    // reference for our X resources
+    // Send the parent our X socket to act as a proxy reference for our X
+    // resources.
     int xSocketFd = ConnectionNumber(DefaultXDisplay());
-    SendBackUpXResources(FileDescriptor(xSocketFd, false/*don't close*/));
+    SendBackUpXResources(FileDescriptor(xSocketFd));
 #endif
 
 #if defined(OS_LINUX)
diff --git a/dom/plugins/ipc/PluginModuleParent.cpp b/dom/plugins/ipc/PluginModuleParent.cpp
index 994602bd9cc2..0233b7857294 100644
--- a/dom/plugins/ipc/PluginModuleParent.cpp
+++ b/dom/plugins/ipc/PluginModuleParent.cpp
@@ -689,9 +689,8 @@ PluginModuleParent::RecvBackUpXResources(const FileDescriptor& aXSocketFd)
 #else
     NS_ABORT_IF_FALSE(0 > mPluginXSocketFdDup.get(),
                       "Already backed up X resources??");
-    int fd = aXSocketFd.fd; // Copy to discard |const| qualifier
     mPluginXSocketFdDup.forget();
-    mPluginXSocketFdDup.reset(fd);
+    mPluginXSocketFdDup.reset(aXSocketFd.PlatformHandle());
 #endif
     return true;
 }
diff --git a/ipc/glue/FileDescriptor.cpp b/ipc/glue/FileDescriptor.cpp
new file mode 100644
index 000000000000..78c3c545836c
--- /dev/null
+++ b/ipc/glue/FileDescriptor.cpp
@@ -0,0 +1,65 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FileDescriptor.h"
+
+#include "mozilla/Assertions.h"
+#include "nsDebug.h"
+
+#ifdef XP_WIN
+#include <windows.h>
+#define INVALID_HANDLE INVALID_HANDLE_VALUE
+#else
+#include <unistd.h>
+#define INVALID_HANDLE -1
+#endif
+
+using mozilla::ipc::FileDescriptor;
+
+FileDescriptor::FileDescriptor()
+: mHandle(INVALID_HANDLE)
+{ }
+
+FileDescriptor::PickleType
+FileDescriptor::ShareTo(const FileDescriptor::IPDLPrivate&,
+                        FileDescriptor::ProcessHandle aOtherProcess) const
+{
+#ifdef XP_WIN
+  if (mHandle == INVALID_HANDLE) {
+    return INVALID_HANDLE;
+  }
+
+  PlatformHandleType newHandle;
+  if (!DuplicateHandle(GetCurrentProcess(), mHandle, aOtherProcess, &newHandle,
+                       0, FALSE, DUPLICATE_SAME_ACCESS)) {
+    NS_WARNING("Failed to duplicate file handle!");
+    return INVALID_HANDLE;
+  }
+
+  return newHandle;
+#else // XP_WIN
+  if (mHandle == INVALID_HANDLE) {
+    return base::FileDescriptor();
+  }
+
+  PlatformHandleType newHandle = dup(mHandle);
+  if (newHandle < 0) {
+    NS_WARNING("Failed to duplicate file descriptor!");
+    return base::FileDescriptor();
+  }
+
+  // This file descriptor must be closed once the caller is done using it, so
+  // pass true here for the 'auto_close' argument.
+  return base::FileDescriptor(newHandle, true);
+#endif
+
+  MOZ_NOT_REACHED("Must not get here!");
+  return PickleType();
+}
+
+bool
+FileDescriptor::IsValid() const
+{
+  return mHandle != INVALID_HANDLE;
+}
diff --git a/ipc/glue/FileDescriptor.h b/ipc/glue/FileDescriptor.h
new file mode 100644
index 000000000000..26f8ad1df537
--- /dev/null
+++ b/ipc/glue/FileDescriptor.h
@@ -0,0 +1,95 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ipc_FileDescriptor_h
+#define mozilla_ipc_FileDescriptor_h
+
+#include "base/basictypes.h"
+#include "base/process.h"
+#include "nscore.h"
+
+#ifdef XP_WIN
+// Need the HANDLE typedef.
+#include <winnt.h>
+#else
+#include "base/file_descriptor_posix.h"
+#endif
+
+namespace mozilla {
+namespace ipc {
+
+// This class is used by IPDL to share file descriptors across processes. When
+// sending a FileDescriptor IPDL will first duplicate a platform-specific file
+// handle type ('PlatformHandleType') into a handle that is valid in the other
+// process. Then IPDL will convert the duplicated handle into a type suitable
+// for pickling ('PickleType') and then send that through the IPC pipe. In the
+// receiving process the pickled data is converted into a platform-specific file
+// handle and then returned to the receiver.
+//
+// To use this class add 'FileDescriptor' as an argument in the IPDL protocol
+// and then pass a file descriptor from C++ to the Call/Send method. The
+// Answer/Recv method will receive a FileDescriptor& on which PlatformHandle()
+// can be called to return the platform file handle.
+class FileDescriptor
+{
+public:
+  typedef base::ProcessHandle ProcessHandle;
+
+#ifdef XP_WIN
+  typedef HANDLE PlatformHandleType;
+  typedef HANDLE PickleType;
+#else
+  typedef int PlatformHandleType;
+  typedef base::FileDescriptor PickleType;
+#endif
+
+  // This should only ever be created by IPDL.
+  struct IPDLPrivate
+  {};
+
+  FileDescriptor();
+
+  FileDescriptor(PlatformHandleType aHandle)
+  : mHandle(aHandle)
+  { }
+
+  FileDescriptor(const IPDLPrivate&, const PickleType& aPickle)
+#ifdef XP_WIN
+  : mHandle(aPickle)
+#else
+  : mHandle(aPickle.fd)
+#endif
+  { }
+
+  // Performs platform-specific actions to duplicate mHandle in the other
+  // process (e.g. dup() on POSIX, DuplicateHandle() on Windows). Returns a
+  // pickled value that can be passed to the other process via IPC.
+  PickleType
+  ShareTo(const IPDLPrivate&, ProcessHandle aOtherProcess) const;
+
+  // Tests mHandle against a well-known invalid platform-specific file handle
+  // (e.g. -1 on POSIX, INVALID_HANDLE_VALUE on Windows).
+  bool
+  IsValid() const;
+
+  PlatformHandleType
+  PlatformHandle() const
+  {
+    return mHandle;
+  }
+
+  bool
+  operator==(const FileDescriptor& aOther) const
+  {
+    return mHandle == aOther.mHandle;
+  }
+
+private:
+  PlatformHandleType mHandle;
+};
+
+} // namespace ipc
+} // namespace mozilla
+
+#endif // mozilla_ipc_FileDescriptor_h
diff --git a/ipc/glue/IPCSerializableParams.ipdlh b/ipc/glue/IPCSerializableParams.ipdlh
new file mode 100644
index 000000000000..21acd68508de
--- /dev/null
+++ b/ipc/glue/IPCSerializableParams.ipdlh
@@ -0,0 +1,44 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+namespace mozilla {
+namespace ipc {
+
+struct StringInputStreamParams
+{
+  nsCString data;
+};
+
+struct FileInputStreamParams
+{
+  FileDescriptor file;
+  int32_t behaviorFlags;
+  int32_t ioFlags;
+};
+
+struct PartialFileInputStreamParams
+{
+  FileInputStreamParams fileStreamParams;
+  uint64_t begin;
+  uint64_t length;
+};
+
+struct MultiplexInputStreamParams
+{
+  InputStreamParams[] streams;
+  uint32_t currentStream;
+  nsresult status;
+  bool startedReadingCurrent;
+};
+
+union InputStreamParams
+{
+  StringInputStreamParams;
+  FileInputStreamParams;
+  PartialFileInputStreamParams;
+  MultiplexInputStreamParams;
+};
+
+} // namespace ipc
+} // namespace mozilla
diff --git a/ipc/glue/InputStreamUtils.cpp b/ipc/glue/InputStreamUtils.cpp
new file mode 100644
index 000000000000..533326210bb8
--- /dev/null
+++ b/ipc/glue/InputStreamUtils.cpp
@@ -0,0 +1,79 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "InputStreamUtils.h"
+
+#include "nsIIPCSerializableInputStream.h"
+
+#include "mozilla/Assertions.h"
+#include "nsComponentManagerUtils.h"
+#include "nsDebug.h"
+#include "nsID.h"
+#include "nsMultiplexInputStream.h"
+#include "nsNetCID.h"
+#include "nsStringStream.h"
+#include "nsThreadUtils.h"
+
+using namespace mozilla::ipc;
+
+namespace {
+
+NS_DEFINE_CID(kStringInputStreamCID, NS_STRINGINPUTSTREAM_CID);
+NS_DEFINE_CID(kFileInputStreamCID, NS_LOCALFILEINPUTSTREAM_CID);
+NS_DEFINE_CID(kPartialFileInputStreamCID, NS_PARTIALLOCALFILEINPUTSTREAM_CID);
+NS_DEFINE_CID(kMultiplexInputStreamCID, NS_MULTIPLEXINPUTSTREAM_CID);
+
+} // anonymous namespace
+
+namespace mozilla {
+namespace ipc {
+
+already_AddRefed<nsIInputStream>
+DeserializeInputStream(const InputStreamParams& aParams)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  nsCOMPtr<nsIIPCSerializableInputStream> serializable;
+
+  switch (aParams.type()) {
+    case InputStreamParams::T__None:
+      NS_WARNING("This union has no type!");
+      return nullptr;
+
+    case InputStreamParams::TStringInputStreamParams:
+      serializable = do_CreateInstance(kStringInputStreamCID);
+      break;
+
+    case InputStreamParams::TFileInputStreamParams:
+      serializable = do_CreateInstance(kFileInputStreamCID);
+      break;
+
+    case InputStreamParams::TPartialFileInputStreamParams:
+      serializable = do_CreateInstance(kPartialFileInputStreamCID);
+      break;
+
+    case InputStreamParams::TMultiplexInputStreamParams:
+      serializable = do_CreateInstance(kMultiplexInputStreamCID);
+      break;
+
+    default:
+      NS_WARNING("Unknown params!");
+      return nullptr;
+  }
+
+  MOZ_ASSERT(serializable);
+
+  if (!serializable->Deserialize(aParams)) {
+    NS_WARNING("Deserialize failed!");
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIInputStream> stream = do_QueryInterface(serializable);
+  MOZ_ASSERT(stream);
+
+  return stream.forget();
+}
+
+} // namespace ipc
+} // namespace mozilla
diff --git a/ipc/glue/InputStreamUtils.h b/ipc/glue/InputStreamUtils.h
new file mode 100644
index 000000000000..362488cf5894
--- /dev/null
+++ b/ipc/glue/InputStreamUtils.h
@@ -0,0 +1,21 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ipc_InputStreamUtils_h
+#define mozilla_ipc_InputStreamUtils_h
+
+#include "mozilla/ipc/IPCSerializableParams.h"
+#include "nsCOMPtr.h"
+#include "nsIInputStream.h"
+
+namespace mozilla {
+namespace ipc {
+
+already_AddRefed<nsIInputStream>
+DeserializeInputStream(const InputStreamParams& aParams);
+
+} // namespace ipc
+} // namespace mozilla
+
+#endif // mozilla_ipc_InputStreamUtils_h
diff --git a/ipc/glue/Makefile.in b/ipc/glue/Makefile.in
index 77bec25bcc67..467bf4f85e62 100644
--- a/ipc/glue/Makefile.in
+++ b/ipc/glue/Makefile.in
@@ -25,7 +25,9 @@ EXPORTS_mozilla/ipc = \
   AsyncChannel.h \
   BrowserProcessSubThread.h \
   CrossProcessMutex.h \
+  FileDescriptor.h \
   GeckoChildProcessHost.h \
+  InputStreamUtils.h \
   IOThreadChild.h \
   ProcessChild.h \
   ProtocolUtils.h \
@@ -40,6 +42,8 @@ EXPORTS_mozilla/ipc = \
   Transport.h \
   $(NULL)
 
+EXPORTS = nsIIPCSerializableInputStream.h
+
 ifeq ($(OS_ARCH),WINNT) #{
 EXPORTS_mozilla/ipc += \
   Transport_win.h \
@@ -63,7 +67,9 @@ endif #}
 CPPSRCS += \
   AsyncChannel.cpp \
   BrowserProcessSubThread.cpp \
+  FileDescriptor.cpp \
   GeckoChildProcessHost.cpp \
+  InputStreamUtils.cpp \
   MessagePump.cpp \
   ProcessChild.cpp \
   ProtocolUtils.cpp \
diff --git a/ipc/glue/ProtocolUtils.h b/ipc/glue/ProtocolUtils.h
index db4349789738..b5d2890d16e3 100644
--- a/ipc/glue/ProtocolUtils.h
+++ b/ipc/glue/ProtocolUtils.h
@@ -15,6 +15,7 @@
 #include "prenv.h"
 
 #include "IPCMessageStart.h"
+#include "mozilla/ipc/FileDescriptor.h"
 #include "mozilla/ipc/Shmem.h"
 #include "mozilla/ipc/Transport.h"
 
diff --git a/ipc/glue/ipdl.mk b/ipc/glue/ipdl.mk
new file mode 100644
index 000000000000..b2a320c7e60f
--- /dev/null
+++ b/ipc/glue/ipdl.mk
@@ -0,0 +1,5 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+IPDLSRCS = IPCSerializableParams.ipdlh
diff --git a/ipc/glue/nsIIPCSerializableInputStream.h b/ipc/glue/nsIIPCSerializableInputStream.h
new file mode 100644
index 000000000000..2a770180a529
--- /dev/null
+++ b/ipc/glue/nsIIPCSerializableInputStream.h
@@ -0,0 +1,57 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ipc_nsIIPCSerializableInputStream_h
+#define mozilla_ipc_nsIIPCSerializableInputStream_h
+
+#include "nsISupports.h"
+#include "mozilla/Attributes.h"
+
+namespace mozilla {
+namespace ipc {
+class InputStreamParams;
+}
+}
+
+#define NS_IIPCSERIALIZABLEINPUTSTREAM_IID \
+  {0x1f56a3f8, 0xc413, 0x4274, {0x88, 0xe6, 0x68, 0x50, 0x9d, 0xf8, 0x85, 0x2d}}
+
+class NS_NO_VTABLE nsIIPCSerializableInputStream : public nsISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IIPCSERIALIZABLEINPUTSTREAM_IID)
+
+  virtual void
+  Serialize(mozilla::ipc::InputStreamParams& aParams) = 0;
+
+  virtual bool
+  Deserialize(const mozilla::ipc::InputStreamParams& aParams) = 0;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsIIPCSerializableInputStream,
+                              NS_IIPCSERIALIZABLEINPUTSTREAM_IID)
+
+#define NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM \
+  virtual void \
+  Serialize(mozilla::ipc::InputStreamParams&) MOZ_OVERRIDE; \
+  virtual bool \
+  Deserialize(const mozilla::ipc::InputStreamParams&) MOZ_OVERRIDE;
+
+#define NS_FORWARD_NSIIPCSERIALIZABLEINPUTSTREAM(_to) \
+  virtual void \
+  Serialize(mozilla::ipc::InputStreamParams& aParams) MOZ_OVERRIDE \
+  { _to Serialize(aParams); } \
+  virtual bool \
+  Deserialize(const mozilla::ipc::InputStreamParams& aParams) MOZ_OVERRIDE \
+  { return _to Deserialize(aParams); }
+
+#define NS_FORWARD_SAFE_NSIIPCSERIALIZABLEINPUTSTREAM(_to) \
+  virtual void \
+  Serialize(mozilla::ipc::InputStreamParams& aParams) MOZ_OVERRIDE \
+  { if (_to) { _to->Serialize(aParams); } } \
+  virtual bool \
+  Deserialize(const mozilla::ipc::InputStreamParams& aParams) MOZ_OVERRIDE \
+  { if (_to) { return _to->Deserialize(aParams); } return false; }
+
+#endif // mozilla_ipc_nsIIPCSerializableInputStream_h
diff --git a/ipc/ipdl/Makefile.in b/ipc/ipdl/Makefile.in
index dc9032afa938..ff20ce584b02 100644
--- a/ipc/ipdl/Makefile.in
+++ b/ipc/ipdl/Makefile.in
@@ -32,6 +32,7 @@ IPDLDIRS =  \
   dom/src/storage \
   gfx/layers/ipc \
   hal/sandbox \
+  ipc/glue  \
   ipc/testshell  \
   js/ipc  \
   layout/ipc \
diff --git a/ipc/ipdl/ipdl/builtin.py b/ipc/ipdl/ipdl/builtin.py
index 4a600ce9486d..40ed00a7bd6f 100644
--- a/ipc/ipdl/ipdl/builtin.py
+++ b/ipc/ipdl/ipdl/builtin.py
@@ -48,6 +48,7 @@ Types = (
     'nsString',
     'nsCString',
     'mozilla::ipc::Shmem',
+    'mozilla::ipc::FileDescriptor',
 
     # quasi-stdint types used by "public" Gecko headers
     'int8',
diff --git a/ipc/ipdl/ipdl/lower.py b/ipc/ipdl/ipdl/lower.py
index 1fa87ec0fa17..f8f9e2b1d679 100644
--- a/ipc/ipdl/ipdl/lower.py
+++ b/ipc/ipdl/ipdl/lower.py
@@ -233,7 +233,6 @@ def _shmemRevokeRights(shmemexpr):
 def _lookupShmem(idexpr):
     return ExprCall(ExprVar('LookupSharedMemory'), args=[ idexpr ])
 
-
 def _makeForwardDeclForQClass(clsname, quals):
     fd = ForwardDecl(clsname, cls=1)
     if 0 == len(quals):
@@ -492,6 +491,9 @@ class _ConvertToCxxType(TypeVisitor):
     def visitShmemType(self, s):
         return Type(self.typename(s))
 
+    def visitFDType(self, s):
+        return Type(self.typename(s))
+
     def visitProtocolType(self, p): assert 0
     def visitMessageType(self, m): assert 0
     def visitVoidType(self, v): assert 0
@@ -668,6 +670,8 @@ class _StructField(_CompoundTypeComponent):
         refexpr = self.refExpr(thisexpr)
         if 'Shmem' == self.ipdltype.name():
             refexpr = ExprCast(refexpr, Type('Shmem', ref=1), const=1)
+        if 'FileDescriptor' == self.ipdltype.name():
+            refexpr = ExprCast(refexpr, Type('FileDescriptor', ref=1), const=1)
         return refexpr
 
     def argVar(self):
@@ -826,6 +830,8 @@ IPDL union type."""
         # sigh
         if 'Shmem' == self.ipdltype.name():
             v = ExprCast(v, Type('Shmem', ref=1), const=1)
+        if 'FileDescriptor' == self.ipdltype.name():
+            v = ExprCast(v, Type('FileDescriptor', ref=1), const=1)
         return v
 
 ##--------------------------------------------------
@@ -990,7 +996,6 @@ def _subtreeUsesShmem(p):
                 return True
     return False
 
-
 class Protocol(ipdl.ast.Protocol):
     def cxxTypedefs(self):
         return self.decl.cxxtypedefs
@@ -1867,6 +1872,11 @@ stmt.  Some types generate both kinds.'''
         self.visited.add(s)
         self.maybeTypedef('mozilla::ipc::Shmem', 'Shmem')
 
+    def visitFDType(self, s):
+        if s in self.visited: return
+        self.visited.add(s)
+        self.maybeTypedef('mozilla::ipc::FileDescriptor', 'FileDescriptor')
+
     def visitVoidType(self, v): assert 0
     def visitMessageType(self, v): assert 0
     def visitProtocolType(self, v): assert 0
@@ -3379,11 +3389,11 @@ class _GenerateProtocolActorCode(ipdl.ast.Visitor):
         p = self.protocol
         routedvar = ExprVar('aRouted')
         idvar = ExprVar('aId')
-        shmemvar = ExprVar('aShmem')
+        shmemvar = ExprVar('shmem')
         rawvar = ExprVar('segment')
         sizevar = ExprVar('aSize')
-        typevar = ExprVar('type')
-        unsafevar = ExprVar('unsafe')
+        typevar = ExprVar('aType')
+        unsafevar = ExprVar('aUnsafe')
         listenertype = Type('ChannelListener', ptr=1)
 
         register = MethodDefn(MethodDecl(
@@ -3978,8 +3988,9 @@ class _GenerateProtocolActorCode(ipdl.ast.Visitor):
         # pickling for IPDL types
         specialtypes = set()
         class findSpecialTypes(TypeVisitor):
-            def visitActorType(self, a):  specialtypes.add(a)
-            def visitShmemType(self, s):  specialtypes.add(s)
+            def visitActorType(self, a): specialtypes.add(a)
+            def visitShmemType(self, s): specialtypes.add(s)
+            def visitFDType(self, s): specialtypes.add(s)
             def visitStructType(self, s):
                 specialtypes.add(s)
                 return TypeVisitor.visitStructType(self, s)
@@ -4006,6 +4017,7 @@ class _GenerateProtocolActorCode(ipdl.ast.Visitor):
             if t.isActor():    self.implementActorPickling(t)
             elif t.isArray():  self.implementSpecialArrayPickling(t)
             elif t.isShmem():  self.implementShmemPickling(t)
+            elif t.isFD():     self.implementFDPickling(t)
             elif t.isStruct(): self.implementStructPickling(t)
             elif t.isUnion():  self.implementUnionPickling(t)
             else:
@@ -4225,6 +4237,57 @@ class _GenerateProtocolActorCode(ipdl.ast.Visitor):
 
         self.cls.addstmts([ write, Whitespace.NL, read, Whitespace.NL ])
 
+    def implementFDPickling(self, fdtype):
+        msgvar = self.msgvar
+        itervar = self.itervar
+        var = self.var
+        tmpvar = ExprVar('fd')
+        picklevar = ExprVar('pfd')
+        intype = _cxxConstRefType(fdtype, self.side)
+        outtype = _cxxPtrToType(fdtype, self.side)
+
+        def _fdType():
+            return Type('FileDescriptor')
+
+        def _fdPickleType():
+            return Type('FileDescriptor::PickleType')
+
+        def _fdBackstagePass():
+            return ExprCall(ExprVar('FileDescriptor::IPDLPrivate'))
+
+        write = MethodDefn(self.writeMethodDecl(intype, var))
+        write.addstmts([
+            StmtDecl(Decl(_fdPickleType(), picklevar.name),
+                     init=ExprCall(ExprSelect(var, '.', 'ShareTo'),
+                                   args=[ _fdBackstagePass(),
+                                          self.protocol.callOtherProcess() ])),
+            StmtExpr(ExprCall(ExprVar('IPC::WriteParam'),
+                              args=[ msgvar, picklevar ])),
+        ])
+
+        read = MethodDefn(self.readMethodDecl(outtype, var))
+        ifread = StmtIf(ExprNot(ExprCall(ExprVar('IPC::ReadParam'),
+                                         args=[ msgvar, itervar,
+                                                ExprAddrOf(picklevar) ])))
+        ifread.addifstmt(StmtReturn.FALSE)
+
+        ifnvalid = StmtIf(ExprNot(ExprCall(ExprSelect(tmpvar, '.', 'IsValid'))))
+        ifnvalid.addifstmt(StmtReturn.FALSE)
+
+        read.addstmts([
+            StmtDecl(Decl(_fdPickleType(), picklevar.name)),
+            ifread,
+            Whitespace.NL,
+            StmtDecl(Decl(_fdType(), tmpvar.name),
+                     init=ExprCall(ExprVar('FileDescriptor'),
+                                   args=[ _fdBackstagePass(), picklevar ])),
+            ifnvalid,
+            Whitespace.NL,
+            StmtExpr(ExprAssn(ExprDeref(var), tmpvar)),
+            StmtReturn.TRUE
+        ])
+
+        self.cls.addstmts([ write, Whitespace.NL, read, Whitespace.NL ])
 
     def implementStructPickling(self, structtype):
         msgvar = self.msgvar
diff --git a/ipc/ipdl/ipdl/type.py b/ipc/ipdl/ipdl/type.py
index 8ed6c214843f..b30534f22f35 100644
--- a/ipc/ipdl/ipdl/type.py
+++ b/ipc/ipdl/ipdl/type.py
@@ -89,6 +89,9 @@ class TypeVisitor:
     def visitShmemChmodType(self, c, *args):
         c.shmem.accept(self)
 
+    def visitFDType(self, s, *args):
+        pass
+
 
 class Type:
     def __cmp__(self, o):
@@ -196,6 +199,7 @@ class IPDLType(Type):
     def isCompound(self): return False
     def isShmem(self): return False
     def isChmod(self): return False
+    def isFD(self): return False
 
     def isAsync(self): return self.sendSemantics is ASYNC
     def isSync(self): return self.sendSemantics is SYNC
@@ -417,6 +421,16 @@ class ShmemType(IPDLType):
     def fullname(self):
         return str(self.qname)
 
+class FDType(IPDLType):
+    def __init__(self, qname):
+        self.qname = qname
+    def isFD(self): return True
+
+    def name(self):
+        return self.qname.baseid
+    def fullname(self):
+        return str(self.qname)
+
 def iteractortypes(t, visited=None):
     """Iterate over any actor(s) buried in |type|."""
     if visited is None:
@@ -452,6 +466,17 @@ def hasshmem(type):
         return True
     return False
 
+def hasfd(type):
+    """Return true iff |type| is fd or has it buried within."""
+    class found: pass
+    class findFD(TypeVisitor):
+        def visitFDType(self, s):  raise found()
+    try:
+        type.accept(findFD())
+    except found:
+        return True
+    return False
+
 ##--------------------
 _builtinloc = Loc('<builtin>', 0)
 def makeBuiltinUsing(tname):
@@ -775,6 +800,8 @@ class GatherDecls(TcheckVisitor):
             fullname = None
         if fullname == 'mozilla::ipc::Shmem':
             ipdltype = ShmemType(using.type.spec)
+        elif fullname == 'mozilla::ipc::FileDescriptor':
+            ipdltype = FDType(using.type.spec)
         else:
             ipdltype = ImportedCxxType(using.type.spec)
         using.decl = self.declare(
diff --git a/netwerk/base/public/Makefile.in b/netwerk/base/public/Makefile.in
index d13ef0b9b8ed..57a136c6ed03 100644
--- a/netwerk/base/public/Makefile.in
+++ b/netwerk/base/public/Makefile.in
@@ -52,7 +52,7 @@ XPIDLSRCS	= \
 		nsIInputStreamPump.idl \
 		nsIInputStreamChannel.idl \
                 nsIIOService2.idl \
-                nsIIPCSerializable.idl \
+                nsIIPCSerializableObsolete.idl \
 		nsIMIMEInputStream.idl \
 		nsINetAddr.idl \
                 nsINetworkLinkService.idl \
diff --git a/netwerk/base/public/nsIIPCSerializable.idl b/netwerk/base/public/nsIIPCSerializableObsolete.idl
similarity index 93%
rename from netwerk/base/public/nsIIPCSerializable.idl
rename to netwerk/base/public/nsIIPCSerializableObsolete.idl
index 595b454209cf..0a04b5647535 100644
--- a/netwerk/base/public/nsIIPCSerializable.idl
+++ b/netwerk/base/public/nsIIPCSerializableObsolete.idl
@@ -17,7 +17,7 @@ class Message;
 [ptr] native Iterator(void*);
 
 [noscript, uuid(1f605ac7-666b-471f-9864-1a21a95f11c4)]
-interface nsIIPCSerializable : nsISupports
+interface nsIIPCSerializableObsolete : nsISupports
 {
   [notxpcom] boolean read(in ConstMessage msg, in Iterator iter);
   [notxpcom] void write(in Message msg);
diff --git a/netwerk/base/src/nsBufferedStreams.cpp b/netwerk/base/src/nsBufferedStreams.cpp
index 10ea3a101da2..1eb22aa6a7ae 100644
--- a/netwerk/base/src/nsBufferedStreams.cpp
+++ b/netwerk/base/src/nsBufferedStreams.cpp
@@ -252,7 +252,7 @@ NS_INTERFACE_MAP_BEGIN(nsBufferedInputStream)
     NS_INTERFACE_MAP_ENTRY(nsIInputStream)
     NS_INTERFACE_MAP_ENTRY(nsIBufferedInputStream)
     NS_INTERFACE_MAP_ENTRY(nsIStreamBufferAccess)
-    NS_INTERFACE_MAP_ENTRY(nsIIPCSerializable)
+    NS_INTERFACE_MAP_ENTRY(nsIIPCSerializableObsolete)
     NS_IMPL_QUERY_CLASSINFO(nsBufferedInputStream)
 NS_INTERFACE_MAP_END_INHERITING(nsBufferedStream)
 
@@ -261,7 +261,7 @@ NS_IMPL_CI_INTERFACE_GETTER5(nsBufferedInputStream,
                              nsIBufferedInputStream,
                              nsISeekableStream,
                              nsIStreamBufferAccess,
-                             nsIIPCSerializable)
+                             nsIIPCSerializableObsolete)
 
 nsresult
 nsBufferedInputStream::Create(nsISupports *aOuter, REFNSIID aIID, void **aResult)
diff --git a/netwerk/base/src/nsBufferedStreams.h b/netwerk/base/src/nsBufferedStreams.h
index cda118403b70..03a552a7328f 100644
--- a/netwerk/base/src/nsBufferedStreams.h
+++ b/netwerk/base/src/nsBufferedStreams.h
@@ -13,7 +13,7 @@
 #include "nsISeekableStream.h"
 #include "nsIStreamBufferAccess.h"
 #include "nsCOMPtr.h"
-#include "nsIIPCSerializable.h"
+#include "nsIIPCSerializableObsolete.h"
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -60,14 +60,14 @@ protected:
 class nsBufferedInputStream : public nsBufferedStream,
                               public nsIBufferedInputStream,
                               public nsIStreamBufferAccess,
-                              public nsIIPCSerializable
+                              public nsIIPCSerializableObsolete
 {
 public:
     NS_DECL_ISUPPORTS_INHERITED
     NS_DECL_NSIINPUTSTREAM
     NS_DECL_NSIBUFFEREDINPUTSTREAM
     NS_DECL_NSISTREAMBUFFERACCESS
-    NS_DECL_NSIIPCSERIALIZABLE
+    NS_DECL_NSIIPCSERIALIZABLEOBSOLETE
 
     nsBufferedInputStream() : nsBufferedStream() {}
     virtual ~nsBufferedInputStream() {}
diff --git a/netwerk/base/src/nsFileStreams.cpp b/netwerk/base/src/nsFileStreams.cpp
index 4b705c30558f..9f0b7876b60d 100644
--- a/netwerk/base/src/nsFileStreams.cpp
+++ b/netwerk/base/src/nsFileStreams.cpp
@@ -28,9 +28,14 @@
 #include "nsReadLine.h"
 #include "nsNetUtil.h"
 #include "nsIClassInfoImpl.h"
+#include "mozilla/ipc/IPCSerializableParams.h"
 
 #define NS_NO_INPUT_BUFFERING 1 // see http://bugzilla.mozilla.org/show_bug.cgi?id=41067
 
+typedef mozilla::ipc::FileDescriptor::PlatformHandleType FileHandleType;
+
+using namespace mozilla::ipc;
+
 ////////////////////////////////////////////////////////////////////////////////
 // nsFileStreamBase
 
@@ -286,12 +291,16 @@ nsFileStreamBase::CleanUpOpen()
 nsresult
 nsFileStreamBase::DoOpen()
 {
-    NS_PRECONDITION(mOpenParams.localFile, "Must have a file to open");
+    NS_ASSERTION(!mFD, "Already have a file descriptor!");
+    NS_ASSERTION(mOpenParams.localFile, "Must have a file to open");
 
     PRFileDesc* fd;
-    nsresult rv = mOpenParams.localFile->OpenNSPRFileDesc(mOpenParams.ioFlags, mOpenParams.perm, &fd);
+    nsresult rv = mOpenParams.localFile->OpenNSPRFileDesc(mOpenParams.ioFlags,
+                                                          mOpenParams.perm,
+                                                          &fd);
     CleanUpOpen();
-    if (NS_FAILED(rv)) return rv;
+    if (NS_FAILED(rv))
+        return rv;
     mFD = fd;
 
     return NS_OK;
@@ -320,16 +329,16 @@ NS_INTERFACE_MAP_BEGIN(nsFileInputStream)
     NS_INTERFACE_MAP_ENTRY(nsIInputStream)
     NS_INTERFACE_MAP_ENTRY(nsIFileInputStream)
     NS_INTERFACE_MAP_ENTRY(nsILineInputStream)
-    NS_INTERFACE_MAP_ENTRY(nsIIPCSerializable)
+    NS_INTERFACE_MAP_ENTRY(nsIIPCSerializableObsolete)
+    NS_INTERFACE_MAP_ENTRY(nsIIPCSerializableInputStream)
     NS_IMPL_QUERY_CLASSINFO(nsFileInputStream)
 NS_INTERFACE_MAP_END_INHERITING(nsFileStreamBase)
 
-NS_IMPL_CI_INTERFACE_GETTER5(nsFileInputStream,
+NS_IMPL_CI_INTERFACE_GETTER4(nsFileInputStream,
                              nsIInputStream,
                              nsIFileInputStream,
                              nsISeekableStream,
-                             nsILineInputStream,
-                             nsIIPCSerializable)
+                             nsILineInputStream)
 
 nsresult
 nsFileInputStream::Create(nsISupports *aOuter, REFNSIID aIID, void **aResult)
@@ -505,6 +514,76 @@ nsFileInputStream::Write(IPC::Message *aMsg)
     WriteParam(aMsg, mBehaviorFlags);
 }
 
+void
+nsFileInputStream::Serialize(InputStreamParams& aParams)
+{
+    FileInputStreamParams params;
+
+    if (mFD) {
+        FileHandleType fd = FileHandleType(PR_FileDesc2NativeHandle(mFD));
+        NS_ASSERTION(fd, "This should never be null!");
+
+        params.file() = FileDescriptor(fd);
+        NS_ASSERTION(params.file().IsValid(),
+                     "Sending an invalid file descriptor!");
+    } else {
+        NS_WARNING("This file has not been opened (or could not be opened). "
+                   "Sending an invalid file descriptor to the other process!");
+    }
+
+    PRInt32 behaviorFlags = mBehaviorFlags;
+
+    // The other process shouldn't close when it reads the end because it will
+    // not be able to reopen the file later.
+    behaviorFlags &= ~nsIFileInputStream::CLOSE_ON_EOF;
+
+    // The other process will not be able to reopen the file so transferring
+    // this flag is meaningless.
+    behaviorFlags &= ~nsIFileInputStream::REOPEN_ON_REWIND;
+
+    // The other process is going to have an open file descriptor automatically
+    // so transferring this flag is meaningless.
+    behaviorFlags &= ~nsIFileInputStream::DEFER_OPEN;
+
+    params.behaviorFlags() = behaviorFlags;
+    params.ioFlags() = mIOFlags;
+
+    aParams = params;
+}
+
+bool
+nsFileInputStream::Deserialize(const InputStreamParams& aParams)
+{
+    NS_ASSERTION(!mFD, "Already have a file descriptor?!");
+    NS_ASSERTION(!mDeferredOpen, "Deferring open?!");
+    NS_ASSERTION(!mFile, "Should never have a file here!");
+    NS_ASSERTION(!mPerm, "This should always be 0!");
+
+    if (aParams.type() != InputStreamParams::TFileInputStreamParams) {
+        NS_WARNING("Received unknown parameters from the other process!");
+        return false;
+    }
+
+    const FileInputStreamParams& params = aParams.get_FileInputStreamParams();
+
+    const FileDescriptor& fd = params.file();
+    NS_WARN_IF_FALSE(fd.IsValid(), "Received an invalid file descriptor!");
+
+    if (fd.IsValid()) {
+        PRFileDesc* fileDesc = PR_ImportFile(PROsfd(fd.PlatformHandle()));
+        if (!fileDesc) {
+            NS_WARNING("Failed to import file handle!");
+            return false;
+        }
+        mFD = fileDesc;
+    }
+
+    mBehaviorFlags = params.behaviorFlags();
+    mIOFlags = params.ioFlags();
+
+    return true;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // nsPartialFileInputStream
 
@@ -520,16 +599,16 @@ NS_INTERFACE_MAP_BEGIN(nsPartialFileInputStream)
     NS_INTERFACE_MAP_ENTRY(nsIInputStream)
     NS_INTERFACE_MAP_ENTRY(nsIPartialFileInputStream)
     NS_INTERFACE_MAP_ENTRY(nsILineInputStream)
-    NS_INTERFACE_MAP_ENTRY(nsIIPCSerializable)
+    NS_INTERFACE_MAP_ENTRY(nsIIPCSerializableObsolete)
+    NS_INTERFACE_MAP_ENTRY(nsIIPCSerializableInputStream)
     NS_IMPL_QUERY_CLASSINFO(nsPartialFileInputStream)
 NS_INTERFACE_MAP_END_INHERITING(nsFileStreamBase)
 
-NS_IMPL_CI_INTERFACE_GETTER5(nsPartialFileInputStream,
+NS_IMPL_CI_INTERFACE_GETTER4(nsPartialFileInputStream,
                              nsIInputStream,
                              nsIPartialFileInputStream,
                              nsISeekableStream,
-                             nsILineInputStream,
-                             nsIIPCSerializable)
+                             nsILineInputStream)
 
 nsresult
 nsPartialFileInputStream::Create(nsISupports *aOuter, REFNSIID aIID,
@@ -680,6 +759,64 @@ nsPartialFileInputStream::Write(IPC::Message *aMsg)
     nsFileInputStream::Write(aMsg);
 }
 
+void
+nsPartialFileInputStream::Serialize(InputStreamParams& aParams)
+{
+    // Serialize the base class first.
+    InputStreamParams fileParams;
+    nsFileInputStream::Serialize(fileParams);
+
+    if (fileParams.type() != InputStreamParams::TFileInputStreamParams) {
+        NS_ERROR("Base class serialize failed!");
+        return;
+    }
+
+    PartialFileInputStreamParams params;
+
+    params.fileStreamParams() = fileParams.get_FileInputStreamParams();
+    params.begin() = mStart;
+    params.length() = mLength;
+
+    aParams = params;
+}
+
+bool
+nsPartialFileInputStream::Deserialize(const InputStreamParams& aParams)
+{
+    NS_ASSERTION(!mFD, "Already have a file descriptor?!");
+    NS_ASSERTION(!mStart, "Already have a start?!");
+    NS_ASSERTION(!mLength, "Already have a length?!");
+    NS_ASSERTION(!mPosition, "Already have a position?!");
+
+    if (aParams.type() != InputStreamParams::TPartialFileInputStreamParams) {
+        NS_ERROR("Received unknown parameters from the other process!");
+        return false;
+    }
+
+    const PartialFileInputStreamParams& params =
+        aParams.get_PartialFileInputStreamParams();
+
+    // Deserialize the base class first.
+    InputStreamParams fileParams(params.fileStreamParams());
+    if (!nsFileInputStream::Deserialize(fileParams)) {
+        NS_ERROR("Base class deserialize failed!");
+        return false;
+    }
+
+    NS_ASSERTION(mFD, "Must have a file descriptor now!");
+
+    mStart = params.begin();
+    mLength = params.length();
+    mPosition = 0;
+
+    if (!mStart) {
+      return true;
+    }
+
+    // XXX This is so broken. Main thread IO alert.
+    return NS_SUCCEEDED(nsFileInputStream::Seek(NS_SEEK_SET, mStart));
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // nsFileOutputStream
 
diff --git a/netwerk/base/src/nsFileStreams.h b/netwerk/base/src/nsFileStreams.h
index c3b4d2438abb..e2835b9e9037 100644
--- a/netwerk/base/src/nsFileStreams.h
+++ b/netwerk/base/src/nsFileStreams.h
@@ -17,7 +17,8 @@
 #include "nsCOMPtr.h"
 #include "prlog.h"
 #include "prio.h"
-#include "nsIIPCSerializable.h"
+#include "nsIIPCSerializableInputStream.h"
+#include "nsIIPCSerializableObsolete.h"
 
 template<class CharType> class nsLineBuffer;
 
@@ -102,13 +103,15 @@ protected:
 class nsFileInputStream : public nsFileStreamBase,
                           public nsIFileInputStream,
                           public nsILineInputStream,
-                          public nsIIPCSerializable
+                          public nsIIPCSerializableObsolete,
+                          public nsIIPCSerializableInputStream
 {
 public:
     NS_DECL_ISUPPORTS_INHERITED
     NS_DECL_NSIFILEINPUTSTREAM
     NS_DECL_NSILINEINPUTSTREAM
-    NS_DECL_NSIIPCSERIALIZABLE
+    NS_DECL_NSIIPCSERIALIZABLEOBSOLETE
+    NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM
 
     NS_IMETHOD Close();
     NS_IMETHOD Available(PRUint64* _retval)
@@ -131,9 +134,11 @@ public:
     NS_IMETHOD Seek(PRInt32 aWhence, PRInt64 aOffset);
 
     nsFileInputStream()
+      : mIOFlags(0), mPerm(0)
     {
         mLineBuffer = nullptr;
     }
+
     virtual ~nsFileInputStream() 
     {
         Close();
@@ -179,7 +184,12 @@ public:
     using nsFileInputStream::Init;
     NS_DECL_ISUPPORTS_INHERITED
     NS_DECL_NSIPARTIALFILEINPUTSTREAM
-    NS_DECL_NSIIPCSERIALIZABLE
+    NS_DECL_NSIIPCSERIALIZABLEOBSOLETE
+    NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM
+
+    nsPartialFileInputStream()
+      : mStart(0), mLength(0), mPosition(0)
+    { }
 
     NS_IMETHOD Tell(PRInt64 *aResult);
     NS_IMETHOD Available(PRUint64 *aResult);
diff --git a/netwerk/base/src/nsMIMEInputStream.cpp b/netwerk/base/src/nsMIMEInputStream.cpp
index 0878df32fa3a..f77073f208b1 100644
--- a/netwerk/base/src/nsMIMEInputStream.cpp
+++ b/netwerk/base/src/nsMIMEInputStream.cpp
@@ -19,12 +19,12 @@
 #include "nsIStringStream.h"
 #include "nsString.h"
 #include "nsMIMEInputStream.h"
-#include "nsIIPCSerializable.h"
+#include "nsIIPCSerializableObsolete.h"
 #include "nsIClassInfoImpl.h"
 
 class nsMIMEInputStream : public nsIMIMEInputStream,
                           public nsISeekableStream,
-                          public nsIIPCSerializable
+                          public nsIIPCSerializableObsolete
 {
 public:
     nsMIMEInputStream();
@@ -34,7 +34,7 @@ public:
     NS_DECL_NSIINPUTSTREAM
     NS_DECL_NSIMIMEINPUTSTREAM
     NS_DECL_NSISEEKABLESTREAM
-    NS_DECL_NSIIPCSERIALIZABLE
+    NS_DECL_NSIIPCSERIALIZABLEOBSOLETE
     
     NS_METHOD Init();
 
@@ -73,12 +73,12 @@ NS_IMPL_QUERY_INTERFACE4_CI(nsMIMEInputStream,
                             nsIMIMEInputStream,
                             nsIInputStream,
                             nsISeekableStream,
-                            nsIIPCSerializable)
+                            nsIIPCSerializableObsolete)
 NS_IMPL_CI_INTERFACE_GETTER4(nsMIMEInputStream,
                              nsIMIMEInputStream,
                              nsIInputStream,
                              nsISeekableStream,
-                             nsIIPCSerializable)
+                             nsIIPCSerializableObsolete)
 
 nsMIMEInputStream::nsMIMEInputStream() : mAddContentLength(false),
                                          mStartedReading(false)
diff --git a/netwerk/base/src/nsSimpleNestedURI.cpp b/netwerk/base/src/nsSimpleNestedURI.cpp
index df1f8d99304f..9a5822a8dacd 100644
--- a/netwerk/base/src/nsSimpleNestedURI.cpp
+++ b/netwerk/base/src/nsSimpleNestedURI.cpp
@@ -55,7 +55,7 @@ nsSimpleNestedURI::Write(nsIObjectOutputStream* aStream)
     return rv;
 }
 
-// nsIIPCSerializable
+// nsIIPCSerializableObsolete
 
 bool
 nsSimpleNestedURI::Read(const IPC::Message *aMsg, void **aIter)
diff --git a/netwerk/base/src/nsSimpleNestedURI.h b/netwerk/base/src/nsSimpleNestedURI.h
index f60071b8f155..e0122f807a4e 100644
--- a/netwerk/base/src/nsSimpleNestedURI.h
+++ b/netwerk/base/src/nsSimpleNestedURI.h
@@ -36,7 +36,7 @@ public:
 
     NS_DECL_ISUPPORTS_INHERITED
     NS_DECL_NSINESTEDURI
-    NS_DECL_NSIIPCSERIALIZABLE
+    NS_DECL_NSIIPCSERIALIZABLEOBSOLETE
 
     // Overrides for various methods nsSimpleURI implements follow.
   
diff --git a/netwerk/base/src/nsSimpleURI.cpp b/netwerk/base/src/nsSimpleURI.cpp
index 78734f4b50a0..211ffde7de7f 100644
--- a/netwerk/base/src/nsSimpleURI.cpp
+++ b/netwerk/base/src/nsSimpleURI.cpp
@@ -41,7 +41,8 @@ nsSimpleURI::~nsSimpleURI()
 NS_IMPL_ADDREF(nsSimpleURI)
 NS_IMPL_RELEASE(nsSimpleURI)
 NS_INTERFACE_TABLE_HEAD(nsSimpleURI)
-NS_INTERFACE_TABLE5(nsSimpleURI, nsIURI, nsISerializable, nsIIPCSerializable, nsIClassInfo, nsIMutable)
+NS_INTERFACE_TABLE5(nsSimpleURI, nsIURI, nsISerializable,
+                    nsIIPCSerializableObsolete, nsIClassInfo, nsIMutable)
 NS_INTERFACE_TABLE_TO_MAP_SEGUE
   if (aIID.Equals(kThisSimpleURIImplementationCID))
     foundInterface = static_cast<nsIURI*>(this);
@@ -117,7 +118,7 @@ nsSimpleURI::Write(nsIObjectOutputStream* aStream)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// nsIIPCSerializable methods:
+// nsIIPCSerializableObsolete methods:
 
 bool
 nsSimpleURI::Read(const IPC::Message *aMsg, void **aIter)
diff --git a/netwerk/base/src/nsSimpleURI.h b/netwerk/base/src/nsSimpleURI.h
index 32a64b11e960..efe82ecc248b 100644
--- a/netwerk/base/src/nsSimpleURI.h
+++ b/netwerk/base/src/nsSimpleURI.h
@@ -9,7 +9,7 @@
 #include "nsIURL.h"
 #include "nsAgg.h"
 #include "nsISerializable.h"
-#include "nsIIPCSerializable.h"
+#include "nsIIPCSerializableObsolete.h"
 #include "nsString.h"
 #include "nsIClassInfo.h"
 #include "nsIMutable.h"
@@ -25,7 +25,7 @@
 
 class nsSimpleURI : public nsIURI,
                     public nsISerializable,
-                    public nsIIPCSerializable,
+                    public nsIIPCSerializableObsolete,
                     public nsIClassInfo,
                     public nsIMutable,
                     public nsISizeOf
@@ -34,7 +34,7 @@ public:
     NS_DECL_ISUPPORTS
     NS_DECL_NSIURI
     NS_DECL_NSISERIALIZABLE
-    NS_DECL_NSIIPCSERIALIZABLE
+    NS_DECL_NSIIPCSERIALIZABLEOBSOLETE
     NS_DECL_NSICLASSINFO
     NS_DECL_NSIMUTABLE
 
diff --git a/netwerk/base/src/nsStandardURL.cpp b/netwerk/base/src/nsStandardURL.cpp
index 7e53a84e6e00..9397df2141b6 100644
--- a/netwerk/base/src/nsStandardURL.cpp
+++ b/netwerk/base/src/nsStandardURL.cpp
@@ -937,7 +937,7 @@ NS_INTERFACE_MAP_BEGIN(nsStandardURL)
     NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIFileURL, mSupportsFileURL)
     NS_INTERFACE_MAP_ENTRY(nsIStandardURL)
     NS_INTERFACE_MAP_ENTRY(nsISerializable)
-    NS_INTERFACE_MAP_ENTRY(nsIIPCSerializable)
+    NS_INTERFACE_MAP_ENTRY(nsIIPCSerializableObsolete)
     NS_INTERFACE_MAP_ENTRY(nsIClassInfo)
     NS_INTERFACE_MAP_ENTRY(nsIMutable)
     // see nsStandardURL::Equals
@@ -2876,7 +2876,7 @@ nsStandardURL::Write(nsIObjectOutputStream *stream)
 }
 
 //---------------------------------------------------------------------------
-// nsStandardURL::nsIIPCSerializable
+// nsStandardURL::nsIIPCSerializableObsolete
 //---------------------------------------------------------------------------
 
 bool
diff --git a/netwerk/base/src/nsStandardURL.h b/netwerk/base/src/nsStandardURL.h
index 0fe881d9c9d9..0bbba2592a82 100644
--- a/netwerk/base/src/nsStandardURL.h
+++ b/netwerk/base/src/nsStandardURL.h
@@ -10,7 +10,7 @@
 #include "nsDependentString.h"
 #include "nsDependentSubstring.h"
 #include "nsISerializable.h"
-#include "nsIIPCSerializable.h"
+#include "nsIIPCSerializableObsolete.h"
 #include "nsIFileURL.h"
 #include "nsIStandardURL.h"
 #include "nsIFile.h"
@@ -42,7 +42,7 @@ class nsIPrefBranch;
 class nsStandardURL : public nsIFileURL
                     , public nsIStandardURL
                     , public nsISerializable
-                    , public nsIIPCSerializable
+                    , public nsIIPCSerializableObsolete
                     , public nsIClassInfo
                     , public nsISizeOf
 {
@@ -53,7 +53,7 @@ public:
     NS_DECL_NSIFILEURL
     NS_DECL_NSISTANDARDURL
     NS_DECL_NSISERIALIZABLE
-    NS_DECL_NSIIPCSERIALIZABLE
+    NS_DECL_NSIIPCSERIALIZABLEOBSOLETE
     NS_DECL_NSICLASSINFO
     NS_DECL_NSIMUTABLE
 
diff --git a/netwerk/ipc/NeckoMessageUtils.h b/netwerk/ipc/NeckoMessageUtils.h
index 1473bbb0dd92..93b4aa989f9a 100644
--- a/netwerk/ipc/NeckoMessageUtils.h
+++ b/netwerk/ipc/NeckoMessageUtils.h
@@ -9,7 +9,7 @@
 #include "IPC/IPCMessageUtils.h"
 #include "nsStringGlue.h"
 #include "nsIURI.h"
-#include "nsIIPCSerializable.h"
+#include "nsIIPCSerializableObsolete.h"
 #include "nsIClassInfo.h"
 #include "nsComponentManagerUtils.h"
 #include "nsNetUtil.h"
@@ -51,7 +51,8 @@ struct ParamTraits<URI>
     if (isNull)
       return;
     
-    nsCOMPtr<nsIIPCSerializable> serializable = do_QueryInterface(aParam.mURI);
+    nsCOMPtr<nsIIPCSerializableObsolete> serializable =
+      do_QueryInterface(aParam.mURI);
     if (!serializable) {
       nsCString scheme;
       aParam.mURI->GetScheme(scheme);
@@ -120,7 +121,7 @@ struct ParamTraits<URI>
     nsCOMPtr<nsIURI> uri = do_CreateInstance(cid);
     if (!uri)
       return false;
-    nsCOMPtr<nsIIPCSerializable> serializable = do_QueryInterface(uri);
+    nsCOMPtr<nsIIPCSerializableObsolete> serializable = do_QueryInterface(uri);
     if (!serializable || !serializable->Read(aMsg, aIter))
       return false;
 
@@ -170,12 +171,14 @@ struct ParamTraits<InputStream>
     if (isNull)
       return;
 
-    nsCOMPtr<nsIIPCSerializable> serializable = do_QueryInterface(aParam.mStream);
+    nsCOMPtr<nsIIPCSerializableObsolete> serializable =
+      do_QueryInterface(aParam.mStream);
     bool isSerializable = !!serializable;
     WriteParam(aMsg, isSerializable);
 
     if (!serializable) {
-      NS_WARNING("nsIInputStream implementation doesn't support nsIIPCSerializable; falling back to copying data");
+      NS_WARNING("nsIInputStream implementation doesn't support "
+                 "nsIIPCSerializableObsolete; falling back to copying data");
 
       nsCString streamString;
       PRUint64 bytes;
@@ -241,7 +244,8 @@ struct ParamTraits<InputStream>
       stream = do_CreateInstance(cid);
       if (!stream)
         return false;
-      nsCOMPtr<nsIIPCSerializable> serializable = do_QueryInterface(stream);
+      nsCOMPtr<nsIIPCSerializableObsolete> serializable =
+        do_QueryInterface(stream);
       if (!serializable || !serializable->Read(aMsg, aIter))
         return false;
     }
diff --git a/netwerk/protocol/about/nsAboutProtocolHandler.cpp b/netwerk/protocol/about/nsAboutProtocolHandler.cpp
index 8e339aecb601..20d43cf349c0 100644
--- a/netwerk/protocol/about/nsAboutProtocolHandler.cpp
+++ b/netwerk/protocol/about/nsAboutProtocolHandler.cpp
@@ -292,7 +292,7 @@ nsNestedAboutURI::Write(nsIObjectOutputStream* aStream)
     return NS_OK;
 }
 
-// nsIIPCSerializable
+// nsIIPCSerializableObsolete
 bool
 nsNestedAboutURI::Read(const IPC::Message *aMsg, void **aIter)
 {
diff --git a/netwerk/protocol/about/nsAboutProtocolHandler.h b/netwerk/protocol/about/nsAboutProtocolHandler.h
index 4c0b83061b1e..0fa9d85013f6 100644
--- a/netwerk/protocol/about/nsAboutProtocolHandler.h
+++ b/netwerk/protocol/about/nsAboutProtocolHandler.h
@@ -45,7 +45,7 @@ private:
 // Class to allow us to propagate the base URI to about:blank correctly
 class nsNestedAboutURI : public nsSimpleNestedURI {
 public:
-    NS_DECL_NSIIPCSERIALIZABLE
+    NS_DECL_NSIIPCSERIALIZABLEOBSOLETE
 
     nsNestedAboutURI(nsIURI* aInnerURI, nsIURI* aBaseURI)
         : nsSimpleNestedURI(aInnerURI)
diff --git a/netwerk/protocol/http/PHttpChannelParams.h b/netwerk/protocol/http/PHttpChannelParams.h
index 3590592e1240..ff2c60901383 100644
--- a/netwerk/protocol/http/PHttpChannelParams.h
+++ b/netwerk/protocol/http/PHttpChannelParams.h
@@ -15,7 +15,6 @@
 #include "nsHttpHeaderArray.h"
 #include "nsHttpResponseHead.h"
 
-#include "nsIIPCSerializable.h"
 #include "nsIClassInfo.h"
 #include "nsNetUtil.h"
 
diff --git a/xpcom/io/nsMultiplexInputStream.cpp b/xpcom/io/nsMultiplexInputStream.cpp
index 735ede5a08fc..c3bc95226847 100644
--- a/xpcom/io/nsMultiplexInputStream.cpp
+++ b/xpcom/io/nsMultiplexInputStream.cpp
@@ -17,12 +17,18 @@
 #include "nsISeekableStream.h"
 #include "nsCOMPtr.h"
 #include "nsCOMArray.h"
-#include "nsIIPCSerializable.h"
+#include "nsIIPCSerializableObsolete.h"
 #include "nsIClassInfoImpl.h"
+#include "nsIIPCSerializableInputStream.h"
+#include "mozilla/ipc/InputStreamUtils.h"
+#include "mozilla/ipc/IPCSerializableParams.h"
+
+using namespace mozilla::ipc;
 
 class nsMultiplexInputStream MOZ_FINAL : public nsIMultiplexInputStream,
                                          public nsISeekableStream,
-                                         public nsIIPCSerializable
+                                         public nsIIPCSerializableObsolete,
+                                         public nsIIPCSerializableInputStream
 {
 public:
     nsMultiplexInputStream();
@@ -31,7 +37,8 @@ public:
     NS_DECL_NSIINPUTSTREAM
     NS_DECL_NSIMULTIPLEXINPUTSTREAM
     NS_DECL_NSISEEKABLESTREAM
-    NS_DECL_NSIIPCSERIALIZABLE
+    NS_DECL_NSIIPCSERIALIZABLEOBSOLETE
+    NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM
 
 private:
     ~nsMultiplexInputStream() {}
@@ -60,16 +67,16 @@ NS_IMPL_THREADSAFE_RELEASE(nsMultiplexInputStream)
 NS_IMPL_CLASSINFO(nsMultiplexInputStream, NULL, nsIClassInfo::THREADSAFE,
                   NS_MULTIPLEXINPUTSTREAM_CID)
 
-NS_IMPL_QUERY_INTERFACE4_CI(nsMultiplexInputStream,
+NS_IMPL_QUERY_INTERFACE5_CI(nsMultiplexInputStream,
                             nsIMultiplexInputStream,
                             nsIInputStream,
                             nsISeekableStream,
-                            nsIIPCSerializable)
-NS_IMPL_CI_INTERFACE_GETTER4(nsMultiplexInputStream,
+                            nsIIPCSerializableObsolete,
+                            nsIIPCSerializableInputStream)
+NS_IMPL_CI_INTERFACE_GETTER3(nsMultiplexInputStream,
                              nsIMultiplexInputStream,
                              nsIInputStream,
-                             nsISeekableStream,
-                             nsIIPCSerializable)
+                             nsISeekableStream)
 
 nsMultiplexInputStream::nsMultiplexInputStream()
     : mCurrentStream(0),
@@ -447,3 +454,75 @@ nsMultiplexInputStream::Write(IPC::Message *aMsg)
     WriteParam(aMsg, mStartedReadingCurrent);
     WriteParam(aMsg, mStatus);
 }
+
+void
+nsMultiplexInputStream::Serialize(InputStreamParams& aParams)
+{
+    MultiplexInputStreamParams params;
+
+    PRUint32 streamCount = mStreams.Count();
+
+    if (streamCount) {
+        InfallibleTArray<InputStreamParams>& streams = params.streams();
+
+        streams.SetCapacity(streamCount);
+        for (PRUint32 index = 0; index < streamCount; index++) {
+            nsCOMPtr<nsIIPCSerializableInputStream> serializable =
+                do_QueryInterface(mStreams.ObjectAt(index));
+            NS_ASSERTION(serializable, "Child stream isn't serializable!");
+
+            if (serializable) {
+                InputStreamParams childStreamParams;
+                serializable->Serialize(childStreamParams);
+
+                NS_ASSERTION(childStreamParams.type() !=
+                                 InputStreamParams::T__None,
+                             "Serialize failed!");
+
+                streams.AppendElement(childStreamParams);
+            }
+        }
+    }
+
+    params.currentStream() = mCurrentStream;
+    params.status() = mStatus;
+    params.startedReadingCurrent() = mStartedReadingCurrent;
+
+    aParams = params;
+}
+
+bool
+nsMultiplexInputStream::Deserialize(const InputStreamParams& aParams)
+{
+    if (aParams.type() !=
+            InputStreamParams::TMultiplexInputStreamParams) {
+        NS_ERROR("Received unknown parameters from the other process!");
+        return false;
+    }
+
+    const MultiplexInputStreamParams& params =
+        aParams.get_MultiplexInputStreamParams();
+
+    const InfallibleTArray<InputStreamParams>& streams = params.streams();
+
+    PRUint32 streamCount = streams.Length();
+    for (PRUint32 index = 0; index < streamCount; index++) {
+        nsCOMPtr<nsIInputStream> stream =
+            DeserializeInputStream(streams[index]);
+        if (!stream) {
+            NS_WARNING("Deserialize failed!");
+            return false;
+        }
+
+        if (NS_FAILED(AppendStream(stream))) {
+            NS_WARNING("AppendStream failed!");
+            return false;
+        }
+    }
+
+    mCurrentStream = params.currentStream();
+    mStatus = params.status();
+    mStartedReadingCurrent = params.startedReadingCurrent();
+
+    return true;
+}
diff --git a/xpcom/io/nsStringStream.cpp b/xpcom/io/nsStringStream.cpp
index 716dccdc7273..42f32f3ba45b 100644
--- a/xpcom/io/nsStringStream.cpp
+++ b/xpcom/io/nsStringStream.cpp
@@ -19,8 +19,12 @@
 #include "prerror.h"
 #include "plstr.h"
 #include "nsIClassInfoImpl.h"
-#include "nsIIPCSerializable.h"
+#include "nsIIPCSerializableObsolete.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/ipc/IPCSerializableParams.h"
+#include "nsIIPCSerializableInputStream.h"
+
+using namespace mozilla::ipc;
 
 //-----------------------------------------------------------------------------
 // nsIStringInputStream implementation
@@ -29,7 +33,8 @@
 class nsStringInputStream MOZ_FINAL : public nsIStringInputStream
                                     , public nsISeekableStream
                                     , public nsISupportsCString
-                                    , public nsIIPCSerializable
+                                    , public nsIIPCSerializableObsolete
+                                    , public nsIIPCSerializableInputStream
 {
 public:
     NS_DECL_ISUPPORTS
@@ -38,7 +43,8 @@ public:
     NS_DECL_NSISEEKABLESTREAM
     NS_DECL_NSISUPPORTSPRIMITIVE
     NS_DECL_NSISUPPORTSCSTRING
-    NS_DECL_NSIIPCSERIALIZABLE
+    NS_DECL_NSIIPCSERIALIZABLEOBSOLETE
+    NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM
 
     nsStringInputStream()
     {
@@ -80,18 +86,18 @@ NS_IMPL_THREADSAFE_RELEASE(nsStringInputStream)
 
 NS_IMPL_CLASSINFO(nsStringInputStream, NULL, nsIClassInfo::THREADSAFE,
                   NS_STRINGINPUTSTREAM_CID)
-NS_IMPL_QUERY_INTERFACE5_CI(nsStringInputStream,
+NS_IMPL_QUERY_INTERFACE6_CI(nsStringInputStream,
                             nsIStringInputStream,
                             nsIInputStream,
                             nsISupportsCString,
                             nsISeekableStream,
-                            nsIIPCSerializable)
-NS_IMPL_CI_INTERFACE_GETTER5(nsStringInputStream,
+                            nsIIPCSerializableObsolete,
+                            nsIIPCSerializableInputStream)
+NS_IMPL_CI_INTERFACE_GETTER4(nsStringInputStream,
                              nsIStringInputStream,
                              nsIInputStream,
                              nsISupportsCString,
-                             nsISeekableStream,
-                             nsIIPCSerializable)
+                             nsISeekableStream)
 
 /////////
 // nsISupportsCString implementation
@@ -288,7 +294,7 @@ nsStringInputStream::SetEOF()
 }
 
 /////////
-// nsIIPCSerializable implementation
+// nsIIPCSerializableObsolete implementation
 /////////
 
 bool
@@ -316,6 +322,33 @@ nsStringInputStream::Write(IPC::Message *aMsg)
     WriteParam(aMsg, static_cast<const nsCString&>(PromiseFlatCString(mData)));
 }
 
+void
+nsStringInputStream::Serialize(InputStreamParams& aParams)
+{
+    StringInputStreamParams params;
+    params.data() = PromiseFlatCString(mData);
+    aParams = params;
+}
+
+bool
+nsStringInputStream::Deserialize(const InputStreamParams& aParams)
+{
+    if (aParams.type() != InputStreamParams::TStringInputStreamParams) {
+        NS_ERROR("Received unknown parameters from the other process!");
+        return false;
+    }
+
+    const StringInputStreamParams& params =
+        aParams.get_StringInputStreamParams();
+
+    if (NS_FAILED(SetData(params.data()))) {
+        NS_WARNING("SetData failed!");
+        return false;
+    }
+
+    return true;
+}
+
 nsresult
 NS_NewByteInputStream(nsIInputStream** aStreamResult,
                       const char* aStringToRead, PRInt32 aLength,