Bug 1246521: P2. Add MediaDecoder::OwnerHasError method. r=gerald

dom/media/MediaDecoder.cpp

@@ -1042,6 +1042,13 @@ MediaDecoder::IsEndedOrShutdown() const
   return IsEnded() || mPlayState == PLAY_STATE_SHUTDOWN;
 }
 
+bool
+MediaDecoder::OwnerHasError() const
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  return mShuttingDown || mOwner->HasError();
+}
+
 bool
 MediaDecoder::IsEnded() const
 {

dom/media/MediaDecoder.h

@@ -234,6 +234,10 @@ public:
   // Call on the main thread only.
   virtual bool IsEndedOrShutdown() const;
 
+  // Return true if the MediaDecoderOwner's error attribute is not null.
+  // If the MediaDecoder is shutting down, OwnerHasError will return true.
+  bool OwnerHasError() const;
+
 protected:
   // Updates the media duration. This is called while the media is being
   // played, calls before the media has reached loaded metadata are ignored.