Bug 1302350 - part3 : provide a method to know the media-block-state before connecting to the AudioChannelService r=baku

In order to refactor the blocking mechanism, we want to know the blocking state
before calling notifyStartedPlaying().

MozReview-Commit-ID: 3wa2M7qwUAm

--HG--
extra : rebase_source : d128463b7fd892b966d80d5b5f76537819f35bcf

dom/audiochannel/AudioChannelAgent.cpp

@@ -361,3 +361,9 @@ AudioChannelAgent::IsPlayingStarted() const
   return mIsRegToService;
 }
 
+bool
+AudioChannelAgent::ShouldBlockMedia() const
+{
+  return mWindow ?
+    mWindow->GetMediaSuspend() == nsISuspendedTypes::SUSPENDED_BLOCK : false;
+}

dom/audiochannel/AudioChannelAgent.h

@@ -49,6 +49,7 @@ public:
   uint64_t InnerWindowID() const;
 
   bool IsPlayingStarted() const;
+  bool ShouldBlockMedia() const;
 
 private:
   virtual ~AudioChannelAgent();