Bug 1336356 - Ensure MediaDecode::Shutdown() is called by MediaShutdownManager::BlockShutdown(). r=gerald

MozReview-Commit-ID: 80AFMafXoeB

--HG--
extra : rebase_source : 8b51b6c9fe4b83b4639c7ae081854307c4308391
extra : source : 7ca33be035c12485e0d6529c529b0cda914fd405

dom/media/MediaDecoder.cpp

@@ -523,6 +523,22 @@ MediaDecoder::Shutdown()
   mOwner = nullptr;
 }
 
+void
+MediaDecoder::NotifyXPCOMShutdown()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  if (auto owner = GetOwner()) {
+    owner->NotifyXPCOMShutdown();
+  }
+  MOZ_DIAGNOSTIC_ASSERT(IsShutdown());
+
+  // Don't cause grief to release builds by ensuring Shutdown()
+  // is always called during shutdown phase.
+  if (!IsShutdown()) {
+    Shutdown();
+  }
+}
+
 MediaDecoder::~MediaDecoder()
 {
   MOZ_ASSERT(NS_IsMainThread());

dom/media/MediaDecoder.h

@@ -134,6 +134,11 @@ public:
   // thread by the owning object before that object disposes of this object.
   virtual void Shutdown();
 
+  // Notified by the shutdown manager that XPCOM shutdown has begun.
+  // The decoder should notify its owner to drop the reference to the decoder
+  // to prevent further calls into the decoder.
+  void NotifyXPCOMShutdown();
+
   // Start downloading the media. Decode the downloaded data up to the
   // point of the first frame of data.
   // This is called at most once per decoder, after Init().

dom/media/MediaDecoderOwner.h

@@ -142,7 +142,7 @@ public:
   // Called by media decoder when the audible state changed
   virtual void SetAudibleState(bool aAudible) = 0;
 
-  // Notified by the shutdown manager that XPCOM shutdown has begun.
+  // Notified by the decoder that XPCOM shutdown has begun.
   // The decoder owner should call Shutdown() on the decoder and drop the
   // reference to the decoder to prevent further calls into the decoder.
   virtual void NotifyXPCOMShutdown() = 0;

dom/media/MediaShutdownManager.cpp

@@ -154,12 +154,7 @@ MediaShutdownManager::BlockShutdown(nsIAsyncShutdownClient*)
 
   // Iterate over the decoders and shut them down.
   for (auto iter = mDecoders.Iter(); !iter.Done(); iter.Next()) {
-    MediaDecoderOwner* owner = iter.Get()->GetKey()->GetOwner();
-    if (owner) {
-      // The owner will call MediaDecoder::Shutdown() and
-      // drop its reference to the decoder.
-      owner->NotifyXPCOMShutdown();
-    }
+    iter.Get()->GetKey()->NotifyXPCOMShutdown();
     // Check MediaDecoder::Shutdown doesn't call Unregister() synchronously in
     // order not to corrupt our hashtable traversal.
     MOZ_ASSERT(mDecoders.Count() == oldCount);