diff --git a/dom/presentation/ControllerConnectionCollection.cpp b/dom/presentation/ControllerConnectionCollection.cpp
new file mode 100644
index 000000000000..7d3ffe68450c
--- /dev/null
+++ b/dom/presentation/ControllerConnectionCollection.cpp
@@ -0,0 +1,116 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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 "ControllerConnectionCollection.h"
+
+#include "mozilla/ClearOnShutdown.h"
+#include "nsIPresentationService.h"
+#include "PresentationConnection.h"
+
+namespace mozilla {
+namespace dom {
+
+/* static */
+StaticAutoPtr<ControllerConnectionCollection>
+ControllerConnectionCollection::sSingleton;
+
+/* static */ ControllerConnectionCollection*
+ControllerConnectionCollection::GetSingleton()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!sSingleton) {
+    sSingleton = new ControllerConnectionCollection();
+    ClearOnShutdown(&sSingleton);
+  }
+
+  return sSingleton;
+}
+
+ControllerConnectionCollection::ControllerConnectionCollection()
+{
+  MOZ_COUNT_CTOR(ControllerConnectionCollection);
+}
+
+ControllerConnectionCollection::~ControllerConnectionCollection()
+{
+  MOZ_COUNT_DTOR(ControllerConnectionCollection);
+}
+
+void
+ControllerConnectionCollection::AddConnection(
+  PresentationConnection* aConnection,
+  const uint8_t aRole)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  if (aRole != nsIPresentationService::ROLE_CONTROLLER) {
+    MOZ_ASSERT(false, "This is allowed only to be called at controller side.");
+    return;
+  }
+
+  if (!aConnection) {
+    return;
+  }
+
+  WeakPtr<PresentationConnection> connection = aConnection;
+  if (mConnections.Contains(connection)) {
+    return;
+  }
+
+  mConnections.AppendElement(connection);
+}
+
+void
+ControllerConnectionCollection::RemoveConnection(
+  PresentationConnection* aConnection,
+  const uint8_t aRole)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  if (aRole != nsIPresentationService::ROLE_CONTROLLER) {
+    MOZ_ASSERT(false, "This is allowed only to be called at controller side.");
+    return;
+  }
+
+  if (!aConnection) {
+    return;
+  }
+
+  WeakPtr<PresentationConnection> connection = aConnection;
+  mConnections.RemoveElement(connection);
+}
+
+already_AddRefed<PresentationConnection>
+ControllerConnectionCollection::FindConnection(
+  uint64_t aWindowId,
+  const nsAString& aId,
+  const uint8_t aRole)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  if (aRole != nsIPresentationService::ROLE_CONTROLLER) {
+    MOZ_ASSERT(false, "This is allowed only to be called at controller side.");
+    return nullptr;
+  }
+
+  // Loop backwards to allow removing elements in the loop.
+  for (int i = mConnections.Length() - 1; i >= 0; --i) {
+    WeakPtr<PresentationConnection> connection = mConnections[i];
+    if (!connection) {
+      // The connection was destroyed. Remove it from the list.
+      mConnections.RemoveElementAt(i);
+      continue;
+    }
+
+    if (connection->Equals(aWindowId, aId)) {
+      RefPtr<PresentationConnection> matchedConnection = connection.get();
+      return matchedConnection.forget();
+    }
+  }
+
+  return nullptr;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/presentation/ControllerConnectionCollection.h b/dom/presentation/ControllerConnectionCollection.h
new file mode 100644
index 000000000000..c5300fe309f9
--- /dev/null
+++ b/dom/presentation/ControllerConnectionCollection.h
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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_dom_ControllerConnectionCollection_h
+#define mozilla_dom_ControllerConnectionCollection_h
+
+#include "mozilla/StaticPtr.h"
+#include "mozilla/WeakPtr.h"
+#include "nsString.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace dom {
+
+class PresentationConnection;
+
+class ControllerConnectionCollection final
+{
+public:
+  static ControllerConnectionCollection* GetSingleton();
+
+  void AddConnection(PresentationConnection* aConnection,
+                     const uint8_t aRole);
+
+  void RemoveConnection(PresentationConnection* aConnection,
+                        const uint8_t aRole);
+
+  already_AddRefed<PresentationConnection>
+  FindConnection(uint64_t aWindowId,
+                 const nsAString& aId,
+                 const uint8_t aRole);
+
+private:
+  friend class StaticAutoPtr<ControllerConnectionCollection>;
+
+  ControllerConnectionCollection();
+  virtual ~ControllerConnectionCollection();
+
+  static StaticAutoPtr<ControllerConnectionCollection> sSingleton;
+  nsTArray<WeakPtr<PresentationConnection>> mConnections;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_ControllerConnectionCollection_h
diff --git a/dom/presentation/PresentationCallbacks.cpp b/dom/presentation/PresentationCallbacks.cpp
index 23d6d50f7f9f..39bf7a5c36dc 100644
--- a/dom/presentation/PresentationCallbacks.cpp
+++ b/dom/presentation/PresentationCallbacks.cpp
@@ -13,6 +13,7 @@
 #include "PresentationCallbacks.h"
 #include "PresentationRequest.h"
 #include "PresentationConnection.h"
+#include "nsThreadUtils.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
@@ -28,6 +29,7 @@ PresentationRequesterCallback::PresentationRequesterCallback(PresentationRequest
                                                              const nsAString& aSessionId,
                                                              Promise* aPromise)
   : mRequest(aRequest)
+  , mUrl(aUrl)
   , mSessionId(aSessionId)
   , mPromise(aPromise)
 {
@@ -46,10 +48,8 @@ PresentationRequesterCallback::NotifySuccess()
 {
   MOZ_ASSERT(NS_IsMainThread());
 
-  // At the sender side, this function must get called after the transport
-  // channel is ready. So we simply set the connection state as connected.
   RefPtr<PresentationConnection> connection =
-    PresentationConnection::Create(mRequest->GetOwner(), mSessionId,
+    PresentationConnection::Create(mRequest->GetOwner(), mSessionId, mUrl,
                                    nsIPresentationService::ROLE_CONTROLLER);
   if (NS_WARN_IF(!connection)) {
     mPromise->MaybeReject(NS_ERROR_DOM_OPERATION_ERR);
@@ -74,6 +74,74 @@ PresentationRequesterCallback::NotifyError(nsresult aError)
  * Implementation of PresentationRequesterCallback
  */
 
+NS_IMPL_ISUPPORTS_INHERITED0(PresentationReconnectCallback,
+                             PresentationRequesterCallback)
+
+PresentationReconnectCallback::PresentationReconnectCallback(
+                                           PresentationRequest* aRequest,
+                                           const nsAString& aUrl,
+                                           const nsAString& aSessionId,
+                                           Promise* aPromise,
+                                           PresentationConnection* aConnection)
+  : PresentationRequesterCallback(aRequest, aUrl, aSessionId, aPromise)
+  , mConnection(aConnection)
+{
+}
+
+PresentationReconnectCallback::~PresentationReconnectCallback()
+{
+}
+
+NS_IMETHODIMP
+PresentationReconnectCallback::NotifySuccess()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  nsCOMPtr<nsIPresentationService> service =
+    do_GetService(PRESENTATION_SERVICE_CONTRACTID);
+  if (NS_WARN_IF(!service)) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsresult rv = NS_OK;
+  // We found a matched connection with the same window ID, URL, and
+  // the session ID. Resolve the promise with this connection and dispatch
+  // the event.
+  if (mConnection) {
+    mPromise->MaybeResolve(mConnection);
+    rv = mRequest->DispatchConnectionAvailableEvent(mConnection);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  } else {
+    // Use |PresentationRequesterCallback::NotifySuccess| to create a new
+    // connection since we don't find one that can be reused.
+    rv = PresentationRequesterCallback::NotifySuccess();
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    rv = service->UpdateWindowIdBySessionId(mSessionId,
+                                            mRequest->GetOwner()->WindowID());
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  nsString sessionId = nsString(mSessionId);
+  return NS_DispatchToMainThread(
+           NS_NewRunnableFunction([sessionId, service]() -> void {
+             service->BuildTransport(sessionId,
+                                     nsIPresentationService::ROLE_CONTROLLER);
+           }));
+}
+
+NS_IMETHODIMP
+PresentationReconnectCallback::NotifyError(nsresult aError)
+{
+  return PresentationRequesterCallback::NotifyError(aError);
+}
+
 NS_IMPL_ISUPPORTS(PresentationResponderLoadingCallback,
                   nsIWebProgressListener,
                   nsISupportsWeakReference)
diff --git a/dom/presentation/PresentationCallbacks.h b/dom/presentation/PresentationCallbacks.h
index 565fab354c4c..08321b2feaef 100644
--- a/dom/presentation/PresentationCallbacks.h
+++ b/dom/presentation/PresentationCallbacks.h
@@ -20,10 +20,11 @@ class nsIWebProgress;
 namespace mozilla {
 namespace dom {
 
+class PresentationConnection;
 class PresentationRequest;
 class Promise;
 
-class PresentationRequesterCallback final : public nsIPresentationServiceCallback
+class PresentationRequesterCallback : public nsIPresentationServiceCallback
 {
 public:
   NS_DECL_ISUPPORTS
@@ -34,14 +35,33 @@ public:
                                 const nsAString& aSessionId,
                                 Promise* aPromise);
 
-private:
-  ~PresentationRequesterCallback();
+protected:
+  virtual ~PresentationRequesterCallback();
 
   RefPtr<PresentationRequest> mRequest;
+  nsString mUrl;
   nsString mSessionId;
   RefPtr<Promise> mPromise;
 };
 
+class PresentationReconnectCallback final : public PresentationRequesterCallback
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIPRESENTATIONSERVICECALLBACK
+
+  PresentationReconnectCallback(PresentationRequest* aRequest,
+                                const nsAString& aUrl,
+                                const nsAString& aSessionId,
+                                Promise* aPromise,
+                                PresentationConnection* aConnection);
+
+private:
+  virtual ~PresentationReconnectCallback();
+
+  RefPtr<PresentationConnection> mConnection;
+};
+
 class PresentationResponderLoadingCallback final : public nsIWebProgressListener
                                                  , public nsSupportsWeakReference
 {
diff --git a/dom/presentation/PresentationConnection.cpp b/dom/presentation/PresentationConnection.cpp
index 345533071fcd..96a8910d6272 100644
--- a/dom/presentation/PresentationConnection.cpp
+++ b/dom/presentation/PresentationConnection.cpp
@@ -6,6 +6,7 @@
 
 #include "PresentationConnection.h"
 
+#include "ControllerConnectionCollection.h"
 #include "mozilla/AsyncEventDispatcher.h"
 #include "mozilla/dom/DOMException.h"
 #include "mozilla/dom/MessageEvent.h"
@@ -43,10 +44,12 @@ NS_INTERFACE_MAP_END_INHERITING(DOMEventTargetHelper)
 
 PresentationConnection::PresentationConnection(nsPIDOMWindowInner* aWindow,
                                                const nsAString& aId,
+                                               const nsAString& aUrl,
                                                const uint8_t aRole,
                                                PresentationConnectionList* aList)
   : DOMEventTargetHelper(aWindow)
   , mId(aId)
+  , mUrl(aUrl)
   , mState(PresentationConnectionState::Connecting)
   , mOwningConnectionList(aList)
 {
@@ -62,14 +65,24 @@ PresentationConnection::PresentationConnection(nsPIDOMWindowInner* aWindow,
 /* static */ already_AddRefed<PresentationConnection>
 PresentationConnection::Create(nsPIDOMWindowInner* aWindow,
                                const nsAString& aId,
+                               const nsAString& aUrl,
                                const uint8_t aRole,
                                PresentationConnectionList* aList)
 {
   MOZ_ASSERT(aRole == nsIPresentationService::ROLE_CONTROLLER ||
              aRole == nsIPresentationService::ROLE_RECEIVER);
   RefPtr<PresentationConnection> connection =
-    new PresentationConnection(aWindow, aId, aRole, aList);
-  return NS_WARN_IF(!connection->Init()) ? nullptr : connection.forget();
+    new PresentationConnection(aWindow, aId, aUrl, aRole, aList);
+  if (NS_WARN_IF(!connection->Init())) {
+    return nullptr;
+  }
+
+  if (aRole == nsIPresentationService::ROLE_CONTROLLER) {
+    ControllerConnectionCollection::GetSingleton()->AddConnection(connection,
+                                                                  aRole);
+  }
+
+  return connection.forget();
 }
 
 bool
@@ -112,6 +125,11 @@ PresentationConnection::Shutdown()
 
   rv = RemoveFromLoadGroup();
   NS_WARN_IF(NS_FAILED(rv));
+
+  if (mRole == nsIPresentationService::ROLE_CONTROLLER) {
+    ControllerConnectionCollection::GetSingleton()->RemoveConnection(this,
+                                                                     mRole);
+  }
 }
 
 /* virtual */ void
@@ -134,6 +152,12 @@ PresentationConnection::GetId(nsAString& aId) const
   aId = mId;
 }
 
+void
+PresentationConnection::GetUrl(nsAString& aUrl) const
+{
+  aUrl = mUrl;
+}
+
 PresentationConnectionState
 PresentationConnection::State() const
 {
@@ -203,6 +227,15 @@ PresentationConnection::Terminate(ErrorResult& aRv)
   NS_WARN_IF(NS_FAILED(service->TerminateSession(mId, mRole)));
 }
 
+bool
+PresentationConnection::Equals(uint64_t aWindowId,
+                               const nsAString& aId)
+{
+  return GetOwner() &&
+         aWindowId == GetOwner()->WindowID() &&
+         mId.Equals(aId);
+}
+
 NS_IMETHODIMP
 PresentationConnection::NotifyStateChange(const nsAString& aSessionId,
                                           uint16_t aState,
@@ -252,6 +285,8 @@ nsresult
 PresentationConnection::ProcessStateChanged(nsresult aReason)
 {
   switch (mState) {
+    case PresentationConnectionState::Connecting:
+      return NS_OK;
     case PresentationConnectionState::Connected: {
       RefPtr<AsyncEventDispatcher> asyncDispatcher =
         new AsyncEventDispatcher(this, NS_LITERAL_STRING("connect"), false);
@@ -333,6 +368,14 @@ PresentationConnection::NotifyMessage(const nsAString& aSessionId,
   return DispatchMessageEvent(jsData);
 }
 
+NS_IMETHODIMP
+PresentationConnection::NotifyReplaced()
+{
+  return NotifyStateChange(mId,
+                           nsIPresentationSessionListener::STATE_CLOSED,
+                           NS_OK);
+}
+
 nsresult
 PresentationConnection::DispatchConnectionClosedEvent(
   PresentationConnectionClosedReason aReason,
diff --git a/dom/presentation/PresentationConnection.h b/dom/presentation/PresentationConnection.h
index fce1acf63625..b8ca76c00280 100644
--- a/dom/presentation/PresentationConnection.h
+++ b/dom/presentation/PresentationConnection.h
@@ -8,6 +8,7 @@
 #define mozilla_dom_PresentationConnection_h
 
 #include "mozilla/DOMEventTargetHelper.h"
+#include "mozilla/WeakPtr.h"
 #include "mozilla/dom/PresentationConnectionBinding.h"
 #include "mozilla/dom/PresentationConnectionClosedEventBinding.h"
 #include "nsIPresentationListener.h"
@@ -22,6 +23,7 @@ class PresentationConnectionList;
 class PresentationConnection final : public DOMEventTargetHelper
                                    , public nsIPresentationSessionListener
                                    , public nsIRequest
+                                   , public SupportsWeakPtr<PresentationConnection>
 {
 public:
   NS_DECL_ISUPPORTS_INHERITED
@@ -29,10 +31,12 @@ public:
                                            DOMEventTargetHelper)
   NS_DECL_NSIPRESENTATIONSESSIONLISTENER
   NS_DECL_NSIREQUEST
+  MOZ_DECLARE_WEAKREFERENCE_TYPENAME(PresentationConnection)
 
   static already_AddRefed<PresentationConnection>
   Create(nsPIDOMWindowInner* aWindow,
          const nsAString& aId,
+         const nsAString& aUrl,
          const uint8_t aRole,
          PresentationConnectionList* aList = nullptr);
 
@@ -44,6 +48,8 @@ public:
   // WebIDL (public APIs)
   void GetId(nsAString& aId) const;
 
+  void GetUrl(nsAString& aUrl) const;
+
   PresentationConnectionState State() const;
 
   void Send(const nsAString& aData,
@@ -53,6 +59,9 @@ public:
 
   void Terminate(ErrorResult& aRv);
 
+  bool
+  Equals(uint64_t aWindowId, const nsAString& aId);
+
   IMPL_EVENT_HANDLER(connect);
   IMPL_EVENT_HANDLER(close);
   IMPL_EVENT_HANDLER(terminate);
@@ -61,6 +70,7 @@ public:
 private:
   PresentationConnection(nsPIDOMWindowInner* aWindow,
                          const nsAString& aId,
+                         const nsAString& aUrl,
                          const uint8_t aRole,
                          PresentationConnectionList* aList);
 
@@ -84,6 +94,7 @@ private:
   nsresult RemoveFromLoadGroup();
 
   nsString mId;
+  nsString mUrl;
   uint8_t mRole;
   PresentationConnectionState mState;
   RefPtr<PresentationConnectionList> mOwningConnectionList;
diff --git a/dom/presentation/PresentationReceiver.cpp b/dom/presentation/PresentationReceiver.cpp
index d19864f59c5d..1e58edb9061c 100644
--- a/dom/presentation/PresentationReceiver.cpp
+++ b/dom/presentation/PresentationReceiver.cpp
@@ -8,6 +8,7 @@
 
 #include "mozilla/dom/PresentationReceiverBinding.h"
 #include "mozilla/dom/Promise.h"
+#include "nsContentUtils.h"
 #include "nsIPresentationService.h"
 #include "nsServiceManagerUtils.h"
 #include "nsThreadUtils.h"
@@ -56,7 +57,11 @@ PresentationReceiver::Init()
   }
   mWindowId = mOwner->WindowID();
 
-  return true;
+  nsCOMPtr<nsIDocShell> docShell = mOwner->GetDocShell();
+  MOZ_ASSERT(docShell);
+
+  nsContentUtils::GetPresentationURL(docShell, mUrl);
+  return !mUrl.IsEmpty();
 }
 
 void PresentationReceiver::Shutdown()
@@ -96,7 +101,7 @@ PresentationReceiver::NotifySessionConnect(uint64_t aWindowId,
   }
 
   RefPtr<PresentationConnection> connection =
-    PresentationConnection::Create(mOwner, aSessionId,
+    PresentationConnection::Create(mOwner, aSessionId, mUrl,
                                    nsIPresentationService::ROLE_RECEIVER,
                                    mConnectionList);
   if (NS_WARN_IF(!connection)) {
diff --git a/dom/presentation/PresentationReceiver.h b/dom/presentation/PresentationReceiver.h
index f77dcfd4e5ae..5647f1194045 100644
--- a/dom/presentation/PresentationReceiver.h
+++ b/dom/presentation/PresentationReceiver.h
@@ -54,6 +54,7 @@ private:
   uint64_t mWindowId;
 
   nsCOMPtr<nsPIDOMWindowInner> mOwner;
+  nsString mUrl;
   RefPtr<Promise> mGetConnectionListPromise;
   RefPtr<PresentationConnectionList> mConnectionList;
 };
diff --git a/dom/presentation/PresentationRequest.cpp b/dom/presentation/PresentationRequest.cpp
index 4eec65bcb537..f9ed659a11fa 100644
--- a/dom/presentation/PresentationRequest.cpp
+++ b/dom/presentation/PresentationRequest.cpp
@@ -6,6 +6,7 @@
 
 #include "PresentationRequest.h"
 
+#include "ControllerConnectionCollection.h"
 #include "mozilla/dom/PresentationRequestBinding.h"
 #include "mozilla/dom/PresentationConnectionAvailableEvent.h"
 #include "mozilla/dom/Promise.h"
@@ -152,6 +153,118 @@ PresentationRequest::StartWithDevice(const nsAString& aDeviceId,
   return promise.forget();
 }
 
+already_AddRefed<Promise>
+PresentationRequest::Reconnect(const nsAString& aPresentationId,
+                               ErrorResult& aRv)
+{
+  // TODO: Before starting to reconnect, we have to run the prohibits
+  // mixed security contexts algorithm first. This will be implemented
+  // in bug 1254488.
+
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(GetOwner());
+  if (NS_WARN_IF(!global)) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIDocument> doc = GetOwner()->GetExtantDoc();
+  if (NS_WARN_IF(!doc)) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  RefPtr<Promise> promise = Promise::Create(global, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  if (doc->GetSandboxFlags() & SANDBOXED_PRESENTATION) {
+    promise->MaybeReject(NS_ERROR_DOM_SECURITY_ERR);
+    return promise.forget();
+  }
+
+  nsString presentationId = nsString(aPresentationId);
+  nsCOMPtr<nsIRunnable> r =
+    NewRunnableMethod<nsString, RefPtr<Promise>>(
+      this,
+      &PresentationRequest::FindOrCreatePresentationConnection,
+      presentationId,
+      promise);
+
+  if (NS_WARN_IF(NS_FAILED(NS_DispatchToMainThread(r)))) {
+    promise->MaybeReject(NS_ERROR_DOM_OPERATION_ERR);
+  }
+
+  return promise.forget();
+}
+
+void
+PresentationRequest::FindOrCreatePresentationConnection(
+  const nsAString& aPresentationId,
+  Promise* aPromise)
+{
+  MOZ_ASSERT(aPromise);
+
+  if (NS_WARN_IF(!GetOwner())) {
+    aPromise->MaybeReject(NS_ERROR_DOM_OPERATION_ERR);
+    return;
+  }
+
+  RefPtr<PresentationConnection> connection =
+    ControllerConnectionCollection::GetSingleton()->FindConnection(
+      GetOwner()->WindowID(),
+      aPresentationId,
+      nsIPresentationService::ROLE_CONTROLLER);
+
+  if (connection) {
+    nsAutoString url;
+    connection->GetUrl(url);
+    if (url.Equals(mUrl)) {
+      switch (connection->State()) {
+        case PresentationConnectionState::Closed:
+          // We found the matched connection.
+          break;
+        case PresentationConnectionState::Connecting:
+        case PresentationConnectionState::Connected:
+          aPromise->MaybeResolve(connection);
+          return;
+        case PresentationConnectionState::Terminated:
+          // A terminated connection cannot be reused.
+          connection = nullptr;
+          break;
+        default:
+          MOZ_CRASH("Unknown presentation session state.");
+          return;
+      }
+    } else {
+      connection = nullptr;
+    }
+  }
+
+  nsCOMPtr<nsIPresentationService> service =
+    do_GetService(PRESENTATION_SERVICE_CONTRACTID);
+  if(NS_WARN_IF(!service)) {
+    aPromise->MaybeReject(NS_ERROR_DOM_OPERATION_ERR);
+    return;
+  }
+
+  nsCOMPtr<nsIPresentationServiceCallback> callback =
+    new PresentationReconnectCallback(this,
+                                      mUrl,
+                                      aPresentationId,
+                                      aPromise,
+                                      connection);
+
+  nsresult rv =
+    service->ReconnectSession(mUrl,
+                              aPresentationId,
+                              nsIPresentationService::ROLE_CONTROLLER,
+                              callback);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    aPromise->MaybeReject(NS_ERROR_DOM_OPERATION_ERR);
+  }
+}
+
 already_AddRefed<Promise>
 PresentationRequest::GetAvailability(ErrorResult& aRv)
 {
diff --git a/dom/presentation/PresentationRequest.h b/dom/presentation/PresentationRequest.h
index 0278c76617dc..72dbe40fef79 100644
--- a/dom/presentation/PresentationRequest.h
+++ b/dom/presentation/PresentationRequest.h
@@ -36,6 +36,9 @@ public:
   already_AddRefed<Promise> StartWithDevice(const nsAString& aDeviceId,
                                             ErrorResult& aRv);
 
+  already_AddRefed<Promise> Reconnect(const nsAString& aPresentationId,
+                                      ErrorResult& aRv);
+
   already_AddRefed<Promise> GetAvailability(ErrorResult& aRv);
 
   IMPL_EVENT_HANDLER(connectionavailable);
@@ -50,6 +53,9 @@ private:
 
   bool Init();
 
+  void FindOrCreatePresentationConnection(const nsAString& aPresentationId,
+                                          Promise* aPromise);
+
   nsString mUrl;
   RefPtr<PresentationAvailability> mAvailability;
 };
diff --git a/dom/presentation/PresentationService.cpp b/dom/presentation/PresentationService.cpp
index 72acab69e399..499a449b3d94 100644
--- a/dom/presentation/PresentationService.cpp
+++ b/dom/presentation/PresentationService.cpp
@@ -223,6 +223,10 @@ PresentationService::Init()
   if (NS_WARN_IF(NS_FAILED(rv))) {
     return false;
   }
+  rv = obs->AddObserver(this, PRESENTATION_RECONNECT_REQUEST_TOPIC, false);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return false;
+  }
 
   nsCOMPtr<nsIPresentationDeviceManager> deviceManager =
     do_GetService(PRESENTATION_DEVICE_MANAGER_CONTRACTID);
@@ -258,6 +262,13 @@ PresentationService::Observe(nsISupports* aSubject,
     }
 
     return HandleTerminateRequest(request);
+  } else if (!strcmp(aTopic, PRESENTATION_RECONNECT_REQUEST_TOPIC)) {
+    nsCOMPtr<nsIPresentationSessionRequest> request(do_QueryInterface(aSubject));
+    if (NS_WARN_IF(!request)) {
+      return NS_ERROR_FAILURE;
+    }
+
+    return HandleReconnectRequest(request);
   } else if (!strcmp(aTopic, "profile-after-change")) {
     // It's expected since we add and entry to |kLayoutCategories| in
     // |nsLayoutModule.cpp| to launch this service earlier.
@@ -285,6 +296,7 @@ PresentationService::HandleShutdown()
     obs->RemoveObserver(this, PRESENTATION_DEVICE_CHANGE_TOPIC);
     obs->RemoveObserver(this, PRESENTATION_SESSION_REQUEST_TOPIC);
     obs->RemoveObserver(this, PRESENTATION_TERMINATE_REQUEST_TOPIC);
+    obs->RemoveObserver(this, PRESENTATION_RECONNECT_REQUEST_TOPIC);
   }
 }
 
@@ -366,12 +378,18 @@ PresentationService::HandleSessionRequest(nsIPresentationSessionRequest* aReques
   // Create or reuse session info.
   RefPtr<PresentationSessionInfo> info =
     GetSessionInfo(sessionId, nsIPresentationService::ROLE_RECEIVER);
-  if (NS_WARN_IF(info)) {
-    // TODO Bug 1195605. Update here after session join/resume becomes supported.
-    ctrlChannel->Disconnect(NS_ERROR_DOM_OPERATION_ERR);
-    return NS_ERROR_DOM_ABORT_ERR;
+
+  // This is the case for reconnecting a session.
+  // Update the control channel and device of the session info.
+  // Call |NotifyResponderReady| to indicate the receiver page is already there.
+  if (info) {
+    info->SetControlChannel(ctrlChannel);
+    info->SetDevice(device);
+    return static_cast<PresentationPresentingInfo*>(
+      info.get())->NotifyResponderReady();
   }
 
+  // This is the case for a new session.
   info = new PresentationPresentingInfo(url, sessionId, device);
   rv = info->Init(ctrlChannel);
   if (NS_WARN_IF(NS_FAILED(rv))) {
@@ -452,6 +470,53 @@ PresentationService::HandleTerminateRequest(nsIPresentationTerminateRequest* aRe
   return info->OnTerminate(ctrlChannel);
 }
 
+nsresult
+PresentationService::HandleReconnectRequest(nsIPresentationSessionRequest* aRequest)
+{
+  nsCOMPtr<nsIPresentationControlChannel> ctrlChannel;
+  nsresult rv = aRequest->GetControlChannel(getter_AddRefs(ctrlChannel));
+  if (NS_WARN_IF(NS_FAILED(rv) || !ctrlChannel)) {
+    return rv;
+  }
+
+  nsAutoString sessionId;
+  rv = aRequest->GetPresentationId(sessionId);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    ctrlChannel->Disconnect(rv);
+    return rv;
+  }
+
+  uint64_t windowId;
+  rv = GetWindowIdBySessionIdInternal(sessionId, &windowId);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    ctrlChannel->Disconnect(rv);
+    return rv;
+  }
+
+  RefPtr<PresentationSessionInfo> info =
+    GetSessionInfo(sessionId, nsIPresentationService::ROLE_RECEIVER);
+  if (NS_WARN_IF(!info)) {
+    // Cannot reconnect non-existed session
+    ctrlChannel->Disconnect(NS_ERROR_DOM_OPERATION_ERR);
+    return NS_ERROR_DOM_ABORT_ERR;
+  }
+
+  nsAutoString url;
+  rv = aRequest->GetUrl(url);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    ctrlChannel->Disconnect(rv);
+    return rv;
+  }
+
+  // Make sure the url is the same as the previous one.
+  if (NS_WARN_IF(!info->GetUrl().Equals(url))) {
+    ctrlChannel->Disconnect(rv);
+    return rv;
+  }
+
+  return HandleSessionRequest(aRequest);
+}
+
 void
 PresentationService::NotifyAvailableChange(bool aIsAvailable)
 {
@@ -642,6 +707,57 @@ PresentationService::TerminateSession(const nsAString& aSessionId,
   return info->Close(NS_OK, nsIPresentationSessionListener::STATE_TERMINATED);
 }
 
+NS_IMETHODIMP
+PresentationService::ReconnectSession(const nsAString& aUrl,
+                                      const nsAString& aSessionId,
+                                      uint8_t aRole,
+                                      nsIPresentationServiceCallback* aCallback)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!aSessionId.IsEmpty());
+  MOZ_ASSERT(aCallback);
+
+  if (aRole != nsIPresentationService::ROLE_CONTROLLER) {
+    MOZ_ASSERT(false, "Only controller can call ReconnectSession.");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (NS_WARN_IF(!aCallback)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  RefPtr<PresentationSessionInfo> info = GetSessionInfo(aSessionId, aRole);
+  if (NS_WARN_IF(!info)) {
+    return aCallback->NotifyError(NS_ERROR_DOM_NOT_FOUND_ERR);
+  }
+
+  if (NS_WARN_IF(!info->GetUrl().Equals(aUrl))) {
+    return aCallback->NotifyError(NS_ERROR_DOM_NOT_FOUND_ERR);
+  }
+
+  return static_cast<PresentationControllingInfo*>(info.get())->Reconnect(aCallback);
+}
+
+NS_IMETHODIMP
+PresentationService::BuildTransport(const nsAString& aSessionId,
+                                    uint8_t aRole)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!aSessionId.IsEmpty());
+
+  if (aRole != nsIPresentationService::ROLE_CONTROLLER) {
+    MOZ_ASSERT(false, "Only controller can call BuildTransport.");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  RefPtr<PresentationSessionInfo> info = GetSessionInfo(aSessionId, aRole);
+  if (NS_WARN_IF(!info)) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  return static_cast<PresentationControllingInfo*>(info.get())->BuildTransport();
+}
+
 NS_IMETHODIMP
 PresentationService::RegisterAvailabilityListener(nsIPresentationAvailabilityListener* aListener)
 {
@@ -848,6 +964,13 @@ PresentationService::GetWindowIdBySessionId(const nsAString& aSessionId,
   return GetWindowIdBySessionIdInternal(aSessionId, aWindowId);
 }
 
+NS_IMETHODIMP
+PresentationService::UpdateWindowIdBySessionId(const nsAString& aSessionId,
+                                               const uint64_t aWindowId)
+{
+  return UpdateWindowIdBySessionIdInternal(aSessionId, aWindowId);
+}
+
 bool
 PresentationService::IsSessionAccessible(const nsAString& aSessionId,
                                          const uint8_t aRole,
diff --git a/dom/presentation/PresentationService.h b/dom/presentation/PresentationService.h
index 913b0e2dfe23..602017be5ef6 100644
--- a/dom/presentation/PresentationService.h
+++ b/dom/presentation/PresentationService.h
@@ -68,6 +68,7 @@ private:
   nsresult HandleDeviceChange();
   nsresult HandleSessionRequest(nsIPresentationSessionRequest* aRequest);
   nsresult HandleTerminateRequest(nsIPresentationTerminateRequest* aRequest);
+  nsresult HandleReconnectRequest(nsIPresentationSessionRequest* aRequest);
   void NotifyAvailableChange(bool aIsAvailable);
   bool IsAppInstalled(nsIURI* aUri);
 
diff --git a/dom/presentation/PresentationServiceBase.cpp b/dom/presentation/PresentationServiceBase.cpp
index 7c0674a23a0e..d5eb24c22446 100644
--- a/dom/presentation/PresentationServiceBase.cpp
+++ b/dom/presentation/PresentationServiceBase.cpp
@@ -36,6 +36,8 @@ PresentationServiceBase::GetWindowIdBySessionIdInternal(
   const nsAString& aSessionId,
   uint64_t* aWindowId)
 {
+  MOZ_ASSERT(NS_IsMainThread());
+
   if (mRespondingWindowIds.Get(aSessionId, aWindowId)) {
     return NS_OK;
   }
@@ -46,6 +48,8 @@ void
 PresentationServiceBase::AddRespondingSessionId(uint64_t aWindowId,
                                                 const nsAString& aSessionId)
 {
+  MOZ_ASSERT(NS_IsMainThread());
+
   if (NS_WARN_IF(aWindowId == 0)) {
     return;
   }
@@ -63,6 +67,8 @@ PresentationServiceBase::AddRespondingSessionId(uint64_t aWindowId,
 void
 PresentationServiceBase::RemoveRespondingSessionId(const nsAString& aSessionId)
 {
+  MOZ_ASSERT(NS_IsMainThread());
+
   uint64_t windowId = 0;
   if (mRespondingWindowIds.Get(aSessionId, &windowId)) {
     mRespondingWindowIds.Remove(aSessionId);
@@ -76,5 +82,17 @@ PresentationServiceBase::RemoveRespondingSessionId(const nsAString& aSessionId)
   }
 }
 
+nsresult
+PresentationServiceBase::UpdateWindowIdBySessionIdInternal(
+  const nsAString& aSessionId,
+  const uint64_t aWindowId)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  RemoveRespondingSessionId(aSessionId);
+  AddRespondingSessionId(aWindowId, aSessionId);
+  return NS_OK;
+}
+
 } // namespace dom
 } // namespace mozilla
diff --git a/dom/presentation/PresentationServiceBase.h b/dom/presentation/PresentationServiceBase.h
index d460b08535a4..962b12f1a17b 100644
--- a/dom/presentation/PresentationServiceBase.h
+++ b/dom/presentation/PresentationServiceBase.h
@@ -37,6 +37,8 @@ protected:
   nsresult GetWindowIdBySessionIdInternal(const nsAString& aSessionId, uint64_t* aWindowId);
   void AddRespondingSessionId(uint64_t aWindowId, const nsAString& aSessionId);
   void RemoveRespondingSessionId(const nsAString& aSessionId);
+  nsresult UpdateWindowIdBySessionIdInternal(const nsAString& aSessionId,
+                                             const uint64_t aWindowId);
 
   // Store the responding listener based on the window ID of the (in-process or
   // OOP) receiver page.
diff --git a/dom/presentation/PresentationSessionInfo.cpp b/dom/presentation/PresentationSessionInfo.cpp
index 02065a05ebf9..9590fe245b1b 100644
--- a/dom/presentation/PresentationSessionInfo.cpp
+++ b/dom/presentation/PresentationSessionInfo.cpp
@@ -244,6 +244,10 @@ PresentationSessionInfo::Shutdown(nsresult aReason)
 nsresult
 PresentationSessionInfo::SetListener(nsIPresentationSessionListener* aListener)
 {
+  if (mListener && aListener) {
+    NS_WARN_IF(NS_FAILED(mListener->NotifyReplaced()));
+  }
+
   mListener = aListener;
 
   if (mListener) {
@@ -425,7 +429,8 @@ PresentationSessionInfo::NotifyTransportClosed(nsresult aReason)
   // potential subsequent |Shutdown| calls.
   mTransport = nullptr;
 
-  if (NS_WARN_IF(!IsSessionReady())) {
+  if (NS_WARN_IF(!IsSessionReady() &&
+                 mState == nsIPresentationSessionListener::STATE_CONNECTING)) {
     // It happens before the session is ready. Reply the callback.
     return ReplyError(NS_ERROR_DOM_OPERATION_ERR);
   }
@@ -744,6 +749,10 @@ PresentationControllingInfo::NotifyConnected()
 
   switch (mState) {
     case nsIPresentationSessionListener::STATE_CONNECTING: {
+      nsresult rv = mControlChannel->Launch(GetSessionId(), GetUrl());
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        return rv;
+      }
       Unused << NS_WARN_IF(NS_FAILED(BuildTransport()));
       break;
     }
@@ -758,14 +767,27 @@ PresentationControllingInfo::NotifyConnected()
   return NS_OK;
 }
 
+NS_IMETHODIMP
+PresentationControllingInfo::NotifyReconnected()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mReconnectCallback);
+
+  if (NS_WARN_IF(mState == nsIPresentationSessionListener::STATE_TERMINATED)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  SetStateWithReason(nsIPresentationSessionListener::STATE_CONNECTING, NS_OK);
+  return mReconnectCallback->NotifySuccess();
+}
+
 nsresult
 PresentationControllingInfo::BuildTransport()
 {
   MOZ_ASSERT(NS_IsMainThread());
 
-  nsresult rv = mControlChannel->Launch(GetSessionId(), GetUrl());
-  if (NS_FAILED(rv)) {
-    return rv;
+  if (mState != nsIPresentationSessionListener::STATE_CONNECTING) {
+    return NS_OK;
   }
 
   if (!Preferences::GetBool("dom.presentation.session_transport.data_channel.enable")) {
@@ -807,7 +829,7 @@ PresentationControllingInfo::BuildTransport()
   if (NS_WARN_IF(!dataChannelBuilder)) {
     return NS_ERROR_NOT_AVAILABLE;
   }
-  rv = dataChannelBuilder->
+  nsresult rv = dataChannelBuilder->
          BuildDataChannelTransport(nsIPresentationService::ROLE_CONTROLLER,
                                    window,
                                    this);
@@ -893,6 +915,41 @@ PresentationControllingInfo::OnStopListening(nsIServerSocket* aServerSocket,
   return NS_OK;
 }
 
+nsresult
+PresentationControllingInfo::Reconnect(nsIPresentationServiceCallback* aCallback)
+{
+  if (!aCallback) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  mReconnectCallback = aCallback;
+
+  if (NS_WARN_IF(mState == nsIPresentationSessionListener::STATE_TERMINATED)) {
+    return mReconnectCallback->NotifyError(NS_ERROR_DOM_INVALID_STATE_ERR);
+  }
+
+  nsresult rv = NS_OK;
+  if (!mControlChannel) {
+    nsCOMPtr<nsIPresentationControlChannel> ctrlChannel;
+    rv = mDevice->EstablishControlChannel(getter_AddRefs(ctrlChannel));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return mReconnectCallback->NotifyError(NS_ERROR_DOM_OPERATION_ERR);
+    }
+
+    rv = Init(ctrlChannel);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return mReconnectCallback->NotifyError(NS_ERROR_DOM_OPERATION_ERR);
+    }
+  }
+
+  rv = mControlChannel->Reconnect(mSessionId, GetUrl());
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return mReconnectCallback->NotifyError(rv);
+  }
+
+  return NS_OK;
+}
+
 /**
  * Implementation of PresentationPresentingInfo
  *
@@ -1217,6 +1274,13 @@ PresentationPresentingInfo::NotifyConnected()
   return NS_OK;
 }
 
+NS_IMETHODIMP
+PresentationPresentingInfo::NotifyReconnected()
+{
+  MOZ_ASSERT(false, "NotifyReconnected should not be called at receiver side.");
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 PresentationPresentingInfo::NotifyDisconnected(nsresult aReason)
 {
diff --git a/dom/presentation/PresentationSessionInfo.h b/dom/presentation/PresentationSessionInfo.h
index 3a38c9fd6a29..701db302040c 100644
--- a/dom/presentation/PresentationSessionInfo.h
+++ b/dom/presentation/PresentationSessionInfo.h
@@ -186,6 +186,10 @@ public:
 
   nsresult Init(nsIPresentationControlChannel* aControlChannel) override;
 
+  nsresult Reconnect(nsIPresentationServiceCallback* aCallback);
+
+  nsresult BuildTransport();
+
 private:
   ~PresentationControllingInfo()
   {
@@ -198,9 +202,8 @@ private:
 
   nsresult OnGetAddress(const nsACString& aAddress);
 
-  nsresult BuildTransport();
-
   nsCOMPtr<nsIServerSocket> mServerSocket;
+  nsCOMPtr<nsIPresentationServiceCallback> mReconnectCallback;
 };
 
 // Session info with presenting browsing context (receiver side) behaviors.
diff --git a/dom/presentation/interfaces/nsIPresentationListener.idl b/dom/presentation/interfaces/nsIPresentationListener.idl
index 63ff6d6aca36..a8f568500a4c 100644
--- a/dom/presentation/interfaces/nsIPresentationListener.idl
+++ b/dom/presentation/interfaces/nsIPresentationListener.idl
@@ -33,6 +33,11 @@ interface nsIPresentationSessionListener : nsISupports
    */
   void notifyMessage(in DOMString sessionId,
                      in ACString data);
+
+  /*
+   * Called when this listener is replaced by another one.
+   */
+  void notifyReplaced();
 };
 
 [scriptable, uuid(27f101d7-9ed1-429e-b4f8-43b00e8e111c)]
diff --git a/dom/presentation/interfaces/nsIPresentationService.idl b/dom/presentation/interfaces/nsIPresentationService.idl
index a99518640327..375e6e4c1204 100644
--- a/dom/presentation/interfaces/nsIPresentationService.idl
+++ b/dom/presentation/interfaces/nsIPresentationService.idl
@@ -98,6 +98,21 @@ interface nsIPresentationService : nsISupports
   void terminateSession(in DOMString sessionId,
                         in uint8_t role);
 
+  /*
+   * Reconnect the session.
+   *
+   * @param url: The url of presenting page.
+   * @param sessionId: An ID to identify presentation session.
+   * @param role: Identify the function called by controller or receiver.
+   * @param callback: NotifySuccess() is called when a control channel
+   *                  is opened successfully.
+   *                  Otherwise, NotifyError() is called with a error message.
+   */
+  void reconnectSession(in DOMString url,
+                        in DOMString sessionId,
+                        in uint8_t role,
+                        in nsIPresentationServiceCallback callback);
+
   /*
    * Register an availability listener. Must be called from the main thread.
    *
@@ -191,4 +206,23 @@ interface nsIPresentationService : nsISupports
    * The windowId for building RTCDataChannel session transport
    */
   unsigned long long getWindowIdBySessionId(in DOMString sessionId);
+
+  /*
+   * Update the mapping of the session ID and window ID.
+   *
+   * @param sessionId: An ID to identify presentation session.
+   * @param windowId: The inner window ID associated with the presentation
+   *                  session.
+   */
+  void updateWindowIdBySessionId(in DOMString sessionId,
+                                 in unsigned long long windowId);
+
+  /*
+   * To build the session transport.
+   * NOTE: This function should be only called at controller side.
+   *
+   * @param sessionId: An ID to identify presentation session.
+   * @param role: Identify the function called by controller or receiver.
+   */
+  void buildTransport(in DOMString sessionId, in uint8_t role);
 };
diff --git a/dom/presentation/interfaces/nsIPresentationSessionRequest.idl b/dom/presentation/interfaces/nsIPresentationSessionRequest.idl
index 473b260a1af8..45a0e314cb22 100644
--- a/dom/presentation/interfaces/nsIPresentationSessionRequest.idl
+++ b/dom/presentation/interfaces/nsIPresentationSessionRequest.idl
@@ -9,6 +9,7 @@ interface nsIPresentationControlChannel;
 
 %{C++
 #define PRESENTATION_SESSION_REQUEST_TOPIC "presentation-session-request"
+#define PRESENTATION_RECONNECT_REQUEST_TOPIC "presentation-reconnect-request"
 %}
 
 /*
diff --git a/dom/presentation/ipc/PPresentation.ipdl b/dom/presentation/ipc/PPresentation.ipdl
index 4314b534c12c..7adff62d7a9a 100644
--- a/dom/presentation/ipc/PPresentation.ipdl
+++ b/dom/presentation/ipc/PPresentation.ipdl
@@ -42,12 +42,27 @@ struct TerminateSessionRequest
   uint8_t role;
 };
 
+struct ReconnectSessionRequest
+{
+  nsString url;
+  nsString sessionId;
+  uint8_t role;
+};
+
+struct BuildTransportRequest
+{
+  nsString sessionId;
+  uint8_t role;
+};
+
 union PresentationIPCRequest
 {
   StartSessionRequest;
   SendSessionMessageRequest;
   CloseSessionRequest;
   TerminateSessionRequest;
+  ReconnectSessionRequest;
+  BuildTransportRequest;
 };
 
 sync protocol PPresentation
diff --git a/dom/presentation/ipc/PresentationBuilderChild.cpp b/dom/presentation/ipc/PresentationBuilderChild.cpp
index 0a309dce6f13..1fb69935e0ae 100644
--- a/dom/presentation/ipc/PresentationBuilderChild.cpp
+++ b/dom/presentation/ipc/PresentationBuilderChild.cpp
@@ -5,8 +5,11 @@
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "DCPresentationChannelDescription.h"
+#include "nsComponentManagerUtils.h"
+#include "nsGlobalWindow.h"
 #include "PresentationBuilderChild.h"
 #include "PresentationIPCService.h"
+#include "nsServiceManagerUtils.h"
 
 namespace mozilla {
 namespace dom {
diff --git a/dom/presentation/ipc/PresentationContentSessionInfo.cpp b/dom/presentation/ipc/PresentationContentSessionInfo.cpp
index 72a4b63f30a3..7bcd620bde55 100644
--- a/dom/presentation/ipc/PresentationContentSessionInfo.cpp
+++ b/dom/presentation/ipc/PresentationContentSessionInfo.cpp
@@ -28,12 +28,20 @@ PresentationContentSessionInfo::Init() {
 nsresult
 PresentationContentSessionInfo::Send(const nsAString& aData)
 {
+  if (!mTransport) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
   return mTransport->Send(aData);
 }
 
 nsresult
 PresentationContentSessionInfo::Close(nsresult aReason)
 {
+  if (!mTransport) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
   return mTransport->Close(aReason);
 }
 
diff --git a/dom/presentation/ipc/PresentationIPCService.cpp b/dom/presentation/ipc/PresentationIPCService.cpp
index 7b162ce24f8e..d6eecaf43b65 100644
--- a/dom/presentation/ipc/PresentationIPCService.cpp
+++ b/dom/presentation/ipc/PresentationIPCService.cpp
@@ -131,6 +131,39 @@ PresentationIPCService::TerminateSession(const nsAString& aSessionId,
   return NS_OK;
 }
 
+NS_IMETHODIMP
+PresentationIPCService::ReconnectSession(const nsAString& aUrl,
+                                         const nsAString& aSessionId,
+                                         uint8_t aRole,
+                                         nsIPresentationServiceCallback* aCallback)
+{
+  MOZ_ASSERT(!aSessionId.IsEmpty());
+
+  if (aRole != nsIPresentationService::ROLE_CONTROLLER) {
+    MOZ_ASSERT(false, "Only controller can call ReconnectSession.");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  return SendRequest(aCallback, ReconnectSessionRequest(nsString(aUrl),
+                                                        nsString(aSessionId),
+                                                        aRole));
+}
+
+NS_IMETHODIMP
+PresentationIPCService::BuildTransport(const nsAString& aSessionId,
+                                       uint8_t aRole)
+{
+  MOZ_ASSERT(!aSessionId.IsEmpty());
+
+  if (aRole != nsIPresentationService::ROLE_CONTROLLER) {
+    MOZ_ASSERT(false, "Only controller can call ReconnectSession.");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  return SendRequest(nullptr, BuildTransportRequest(nsString(aSessionId),
+                                                    aRole));
+}
+
 nsresult
 PresentationIPCService::SendRequest(nsIPresentationServiceCallback* aCallback,
                                     const PresentationIPCRequest& aRequest)
@@ -176,6 +209,13 @@ PresentationIPCService::RegisterSessionListener(const nsAString& aSessionId,
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT(aListener);
 
+  nsCOMPtr<nsIPresentationSessionListener> listener;
+  if (mSessionListeners.Get(aSessionId, getter_AddRefs(listener))) {
+    NS_WARN_IF(NS_FAILED(listener->NotifyReplaced()));
+    mSessionListeners.Put(aSessionId, aListener);
+    return NS_OK;
+  }
+
   mSessionListeners.Put(aSessionId, aListener);
   if (sPresentationChild) {
     NS_WARN_IF(!sPresentationChild->SendRegisterSessionHandler(nsString(aSessionId), aRole));
@@ -245,6 +285,13 @@ PresentationIPCService::GetWindowIdBySessionId(const nsAString& aSessionId,
   return GetWindowIdBySessionIdInternal(aSessionId, aWindowId);
 }
 
+NS_IMETHODIMP
+PresentationIPCService::UpdateWindowIdBySessionId(const nsAString& aSessionId,
+                                                  const uint64_t aWindowId)
+{
+  return UpdateWindowIdBySessionIdInternal(aSessionId, aWindowId);
+}
+
 nsresult
 PresentationIPCService::NotifySessionStateChange(const nsAString& aSessionId,
                                                  uint16_t aState,
diff --git a/dom/presentation/ipc/PresentationIPCService.h b/dom/presentation/ipc/PresentationIPCService.h
index c77928cc5264..3eb29fb0f350 100644
--- a/dom/presentation/ipc/PresentationIPCService.h
+++ b/dom/presentation/ipc/PresentationIPCService.h
@@ -62,14 +62,6 @@ private:
   nsRefPtrHashtable<nsUint64HashKey,
                     nsIPresentationRespondingListener> mRespondingListeners;
   RefPtr<PresentationResponderLoadingCallback> mCallback;
-
-  // Store the mapping between the window ID of the OOP page (in this process)
-  // and the ID of the responding session. It's used for an OOP receiver page
-  // to retrieve the correspondent session ID. Besides, also keep the mapping
-  // between the responding session ID and the window ID to help look up the
-  // window ID.
-  nsClassHashtable<nsUint64HashKey, nsString> mRespondingSessionIds;
-  nsDataHashtable<nsStringHashKey, uint64_t> mRespondingWindowIds;
   nsRefPtrHashtable<nsStringHashKey,
                     PresentationContentSessionInfo> mSessionInfos;
 };
diff --git a/dom/presentation/ipc/PresentationParent.cpp b/dom/presentation/ipc/PresentationParent.cpp
index ae583085e1a7..4f7181ee049e 100644
--- a/dom/presentation/ipc/PresentationParent.cpp
+++ b/dom/presentation/ipc/PresentationParent.cpp
@@ -89,6 +89,12 @@ PresentationParent::RecvPPresentationRequestConstructor(
     case PresentationIPCRequest::TTerminateSessionRequest:
       rv = actor->DoRequest(aRequest.get_TerminateSessionRequest());
       break;
+    case PresentationIPCRequest::TReconnectSessionRequest:
+      rv = actor->DoRequest(aRequest.get_ReconnectSessionRequest());
+      break;
+    case PresentationIPCRequest::TBuildTransportRequest:
+      rv = actor->DoRequest(aRequest.get_BuildTransportRequest());
+      break;
     default:
       MOZ_CRASH("Unknown PresentationIPCRequest type");
   }
@@ -242,6 +248,14 @@ PresentationParent::NotifyStateChange(const nsAString& aSessionId,
   return NS_OK;
 }
 
+NS_IMETHODIMP
+PresentationParent::NotifyReplaced()
+{
+  // Do nothing here, since |PresentationIPCService::RegisterSessionListener|
+  // already dealt with this in content process.
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 PresentationParent::NotifyMessage(const nsAString& aSessionId,
                                   const nsACString& aData)
@@ -382,6 +396,48 @@ PresentationRequestParent::DoRequest(const TerminateSessionRequest& aRequest)
   return NotifySuccess();
 }
 
+nsresult
+PresentationRequestParent::DoRequest(const ReconnectSessionRequest& aRequest)
+{
+  MOZ_ASSERT(mService);
+
+  // Validate the accessibility (primarily for receiver side) so that a
+  // compromised child process can't fake the ID.
+  if (NS_WARN_IF(!static_cast<PresentationService*>(mService.get())->
+    IsSessionAccessible(aRequest.sessionId(), aRequest.role(), OtherPid()))) {
+
+    // NOTE: Return NS_ERROR_DOM_NOT_FOUND_ERR here to match the spec.
+    // https://w3c.github.io/presentation-api/#reconnecting-to-a-presentation
+    return NotifyError(NS_ERROR_DOM_NOT_FOUND_ERR);
+  }
+
+  mNeedRegisterBuilder = true;
+  mSessionId = aRequest.sessionId();
+  return mService->ReconnectSession(aRequest.url(),
+                                    aRequest.sessionId(),
+                                    aRequest.role(),
+                                    this);
+}
+
+nsresult
+PresentationRequestParent::DoRequest(const BuildTransportRequest& aRequest)
+{
+  MOZ_ASSERT(mService);
+
+  // Validate the accessibility (primarily for receiver side) so that a
+  // compromised child process can't fake the ID.
+  if (NS_WARN_IF(!static_cast<PresentationService*>(mService.get())->
+                  IsSessionAccessible(aRequest.sessionId(), aRequest.role(), OtherPid()))) {
+    return NotifyError(NS_ERROR_DOM_SECURITY_ERR);
+  }
+
+  nsresult rv = mService->BuildTransport(aRequest.sessionId(), aRequest.role());
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return NotifyError(rv);
+  }
+  return NotifySuccess();
+}
+
 NS_IMETHODIMP
 PresentationRequestParent::NotifySuccess()
 {
diff --git a/dom/presentation/ipc/PresentationParent.h b/dom/presentation/ipc/PresentationParent.h
index f0e27473edc6..e7958ef4eecf 100644
--- a/dom/presentation/ipc/PresentationParent.h
+++ b/dom/presentation/ipc/PresentationParent.h
@@ -113,6 +113,10 @@ private:
 
   nsresult DoRequest(const TerminateSessionRequest& aRequest);
 
+  nsresult DoRequest(const ReconnectSessionRequest& aRequest);
+
+  nsresult DoRequest(const BuildTransportRequest& aRequest);
+
   bool mActorDestroyed = false;
   bool mNeedRegisterBuilder = false;
   nsString mSessionId;
diff --git a/dom/presentation/moz.build b/dom/presentation/moz.build
index df2b50807761..0e95446ff44f 100644
--- a/dom/presentation/moz.build
+++ b/dom/presentation/moz.build
@@ -32,6 +32,7 @@ EXPORTS.mozilla.dom += [
 ]
 
 UNIFIED_SOURCES += [
+    'ControllerConnectionCollection.cpp',
     'DCPresentationChannelDescription.cpp',
     'ipc/PresentationBuilderChild.cpp',
     'ipc/PresentationBuilderParent.cpp',
diff --git a/dom/webidl/PresentationConnection.webidl b/dom/webidl/PresentationConnection.webidl
index 7492237d5231..2be5119c1265 100644
--- a/dom/webidl/PresentationConnection.webidl
+++ b/dom/webidl/PresentationConnection.webidl
@@ -29,6 +29,11 @@ interface PresentationConnection : EventTarget {
   [Constant]
   readonly attribute DOMString id;
 
+  /*
+   * Specifies the connection's presentation URL.
+   */
+  readonly attribute DOMString url;
+
   /*
    * @value "connected", "closed", or "terminated".
    */
diff --git a/dom/webidl/PresentationRequest.webidl b/dom/webidl/PresentationRequest.webidl
index d54c855575ac..83b9e4c58542 100644
--- a/dom/webidl/PresentationRequest.webidl
+++ b/dom/webidl/PresentationRequest.webidl
@@ -24,10 +24,26 @@ interface PresentationRequest : EventTarget {
    * - "AbortError":     User dismiss/cancel the device prompt box.
    * - "NetworkError":   Failed to establish the control channel or data channel.
    * - "TimeoutError":   Presenting page takes too long to load.
+   * - "SecurityError":  This operation is insecure.
    */
   [Throws]
   Promise<PresentationConnection> start();
 
+  /*
+   * A requesting page can use reconnect(presentationId) to reopen a
+   * non-terminated presentation connection.
+   *
+   * The promise is resolved when a new presentation connection is created.
+   * The connection state is "connecting".
+   *
+   * The promise may be rejected duo to one of the following reasons:
+   * - "OperationError": Unexpected error occurs.
+   * - "NotFoundError":  Can not find a presentation connection with the presentationId.
+   * - "SecurityError":  This operation is insecure.
+   */
+  [Throws]
+  Promise<PresentationConnection> reconnect(DOMString presentationId);
+
  /*
   * UA triggers device discovery mechanism periodically and monitor device
   * availability.