Bug 1195051 - Part 2: Mute the destination node when the AudioContext is suspended, and unmute when resumed; r=padenot

dom/media/webaudio/AudioContext.cpp

@@ -855,7 +855,7 @@ AudioContext::Suspend(ErrorResult& aRv)
     return promise.forget();
   }
 
-  Destination()->DestroyAudioChannelAgent();
+  Destination()->Suspend();
 
   MediaStream* ds = DestinationStream();
   if (ds) {
@@ -895,7 +895,7 @@ AudioContext::Resume(ErrorResult& aRv)
     return promise.forget();
   }
 
-  Destination()->CreateAudioChannelAgent();
+  Destination()->Resume();
 
   MediaStream* ds = DestinationStream();
   if (ds) {

dom/media/webaudio/AudioDestinationNode.cpp

@@ -244,6 +244,7 @@ public:
     : AudioNodeEngine(aNode)
     , mVolume(1.0f)
     , mLastInputMuted(true)
+    , mSuspended(false)
   {
     MOZ_ASSERT(aNode);
   }
@@ -256,6 +257,10 @@ public:
     *aOutput = aInput;
     aOutput->mVolume *= mVolume;
 
+    if (mSuspended) {
+      return;
+    }
+
     bool newInputMuted = aInput.IsNull() || aInput.IsMuted();
     if (newInputMuted != mLastInputMuted) {
       mLastInputMuted = newInputMuted;
@@ -274,8 +279,19 @@ public:
     }
   }
 
+  virtual void SetInt32Parameter(uint32_t aIndex, int32_t aParam) override
+  {
+    if (aIndex == SUSPENDED) {
+      mSuspended = !!aParam;
+      if (mSuspended) {
+        mLastInputMuted = true;
+      }
+    }
+  }
+
   enum Parameters {
     VOLUME,
+    SUSPENDED,
   };
 
   virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
@@ -286,6 +302,7 @@ public:
 private:
   float mVolume;
   bool mLastInputMuted;
+  bool mSuspended;
 };
 
 static bool UseAudioChannelService()
@@ -451,6 +468,20 @@ AudioDestinationNode::Unmute()
   SendDoubleParameterToStream(DestinationNodeEngine::VOLUME, 1.0f);
 }
 
+void
+AudioDestinationNode::Suspend()
+{
+  DestroyAudioChannelAgent();
+  SendInt32ParameterToStream(DestinationNodeEngine::SUSPENDED, 1);
+}
+
+void
+AudioDestinationNode::Resume()
+{
+  CreateAudioChannelAgent();
+  SendInt32ParameterToStream(DestinationNodeEngine::SUSPENDED, 0);
+}
+
 void
 AudioDestinationNode::OfflineShutdown()
 {

dom/media/webaudio/AudioDestinationNode.h

@@ -53,6 +53,9 @@ public:
   void Mute();
   void Unmute();
 
+  void Suspend();
+  void Resume();
+
   void StartRendering(Promise* aPromise);
 
   void OfflineShutdown();