Bug 1509132 - Inform the 3rd party tracker window when the storage permission is granted, r=ehsan

This is needed for the LocalStorage Next-Generation project which sends storage
notifications only to content processes with an existing LocalStorage object.

I cannot write a test for this, because the current localStorage all works fine.

dom/base/nsGlobalWindowInner.cpp

@@ -7986,6 +7986,25 @@ nsGlobalWindowInner::ForgetSharedWorker(SharedWorker* aSharedWorker)
   mSharedWorkers.RemoveElement(aSharedWorker);
 }
 
+void
+nsGlobalWindowInner::StorageAccessGranted()
+{
+  // If we have a partitioned localStorage, it's time to replace it with a real
+  // one in order to receive notifications.
+
+  if (mLocalStorage &&
+      mLocalStorage->Type() == Storage::ePartitionedLocalStorage) {
+    IgnoredErrorResult error;
+    GetLocalStorage(error);
+    if (NS_WARN_IF(error.Failed())) {
+      return;
+    }
+
+    MOZ_ASSERT(mLocalStorage &&
+               mLocalStorage->Type() == Storage::eLocalStorage);
+  }
+}
+
 mozilla::dom::TabGroup*
 nsPIDOMWindowInner::TabGroup()
 {

dom/base/nsGlobalWindowInner.h

@@ -1241,6 +1241,11 @@ public:
   // area.
   nsIPrincipal* GetTopLevelStorageAreaPrincipal();
 
+  // This method is called if this window loads a 3rd party tracking resource
+  // and the storage is just been granted. The window can reset the partitioned
+  // storage objects and switch to the first party cookie jar.
+  void StorageAccessGranted();
+
 protected:
   static void NotifyDOMWindowDestroyed(nsGlobalWindowInner* aWindow);
   void NotifyWindowIDDestroyed(const char* aTopic);

toolkit/components/antitracking/AntiTrackingCommon.cpp

@@ -536,6 +536,9 @@ AntiTrackingCommon::AddFirstPartyStorageAccessGrantedFor(nsIPrincipal* aPrincipa
   // Let's store the permission in the current parent window.
   topInnerWindow->SaveStorageAccessGranted(permissionKey);
 
+  // Let's inform the parent window.
+  parentWindow->StorageAccessGranted();
+
   nsIChannel* channel =
     pwin->GetCurrentInnerWindow()->GetExtantDoc()->GetChannel();