Bug 1346880 - Always initialize an AudioChannelAgent when initializing an AudioContext. r=alwu

Differential Revision: https://phabricator.services.mozilla.com/D92644

dom/media/webaudio/AudioContext.cpp

@@ -176,6 +176,7 @@ AudioContext::AudioContext(nsPIDOMWindowInner* aWindow, bool aIsOffline,
   const bool allowedToStart = AutoplayPolicy::IsAllowedToPlay(*this);
   mDestination = new AudioDestinationNode(this, aIsOffline, allowedToStart,
                                           aNumberOfChannels, aLength);
+  mDestination->Init();
   // If an AudioContext is not allowed to start, we would postpone its state
   // transition from `suspended` to `running` until sites explicitly call
   // AudioContext.resume() or AudioScheduledSourceNode.start().

dom/media/webaudio/AudioDestinationNode.cpp

@@ -321,6 +321,18 @@ AudioDestinationNode::AudioDestinationNode(AudioContext* aContext,
   }
 }
 
+void AudioDestinationNode::Init() {
+  if (!mIsOffline) {
+    CreateAudioChannelAgent();
+    nsresult rv = mAudioChannelAgent->NotifyStartedPlaying(
+        AudioChannelService::AudibleState::eNotAudible);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return;
+    }
+    mAudioChannelAgent->PullInitialUpdate();
+  }
+}
+
 AudioDestinationNode::~AudioDestinationNode() {
   ReleaseAudioWakeLockIfExists();
 }

dom/media/webaudio/AudioDestinationNode.h

@@ -42,6 +42,8 @@ class AudioDestinationNode final : public AudioNode,
   uint32_t MaxChannelCount() const;
   void SetChannelCount(uint32_t aChannelCount, ErrorResult& aRv) override;
 
+  void Init();
+
   // Returns the track or null after unlink.
   AudioNodeTrack* Track();