Bug 1580659 - part3 : call 'WindowAudioCaptureChanged()' explicitly. r=chunmin,karlt

Previously `AudioChannelService` called `WindowAudioCaptureChanged()` implicitly whenever we added the agent to the service [1], which made the audio capturing callback happen before finishing registration.

There are two drawbacks,
(1) it's hard to be aware of that the audio capturing callback would be called before finishing `AudioChannelAgent::NotifyStartedPlaying()` [2], which causes unclear call flow.

(2) If someone checks `AudioChannelAgent::IsPlayingStarted()` [3] inside audio capturing callback, then we would find that the `mIsRegToService` is false even if we have registered the agent to `AudioChannelService` because `mIsRegToService` is updated in the last line in the `AudioChannelAgent::NotifyStartedPlaying()`, but the audio capturing callback could be executed before that.

[1] https://searchfox.org/mozilla-central/rev/a777ff11b6d700a698c61e5bd17e73b044304494/dom/audiochannel/AudioChannelService.cpp#723
[2] https://searchfox.org/mozilla-central/rev/a777ff11b6d700a698c61e5bd17e73b044304494/dom/audiochannel/AudioChannelAgent.cpp#144
[3] https://searchfox.org/mozilla-central/rev/a777ff11b6d700a698c61e5bd17e73b044304494/dom/audiochannel/AudioChannelAgent.cpp#285

Differential Revision: https://phabricator.services.mozilla.com/D45750

--HG--
extra : moz-landing-system : lando

dom/audiochannel/AudioChannelAgent.cpp

@@ -155,7 +155,11 @@ AudioChannelAgent::NotifyStartedPlaying(AudioPlaybackConfig* aConfig,
            config.mMuted ? "true" : "false", config.mVolume,
            SuspendTypeToStr(config.mSuspend)));
 
-  aConfig->SetConfig(config.mVolume, config.mMuted, config.mSuspend);
+  aConfig->mVolume = config.mVolume;
+  aConfig->mMuted = config.mMuted;
+  aConfig->mSuspend = config.mSuspend;
+  aConfig->mCapturedAudio = config.mCapturedAudio;
+
   mIsRegToService = true;
   return NS_OK;
 }

dom/audiochannel/AudioChannelService.cpp

@@ -321,7 +321,9 @@ AudioPlaybackConfig AudioChannelService::GetMediaConfig(
   AudioPlaybackConfig config(1.0, false, nsISuspendedTypes::NONE_SUSPENDED);
 
   if (!aWindow) {
-    config.SetConfig(0.0, true, nsISuspendedTypes::SUSPENDED_BLOCK);
+    config.mVolume = 0.0;
+    config.mMuted = true;
+    config.mSuspend = nsISuspendedTypes::SUSPENDED_BLOCK;
     return config;
   }
 
@@ -338,6 +340,7 @@ AudioPlaybackConfig AudioChannelService::GetMediaConfig(
       config.mSuspend = winData->mOwningAudioFocus
                             ? config.mSuspend
                             : nsISuspendedTypes::SUSPENDED_STOP_DISPOSABLE;
+      config.mCapturedAudio = winData->mIsAudioCaptured;
     }
 
     config.mVolume *= window->GetAudioVolume();
@@ -716,7 +719,6 @@ void AudioChannelService::AudioChannelWindow::AppendAgent(
 
   RequestAudioFocus(aAgent);
   AppendAgentAndIncreaseAgentsNum(aAgent);
-  AudioCapturedChanged(aAgent, AudioCaptureState::eCapturing);
   if (aAudible == AudibleState::eAudible) {
     AudioAudibleChanged(aAgent, AudibleState::eAudible,
                         AudibleChangedReasons::eDataAudibleChanged);

dom/audiochannel/AudioChannelService.h

@@ -38,15 +38,10 @@ class AudioPlaybackConfig {
         mSuspend(aSuspended),
         mNumberOfAgents(0) {}
 
-  void SetConfig(float aVolume, bool aMuted, uint32_t aSuspended) {
-    mVolume = aVolume;
-    mMuted = aMuted;
-    mSuspend = aSuspended;
-  }
-
   float mVolume;
   bool mMuted;
   uint32_t mSuspend;
+  bool mCapturedAudio = false;
   uint32_t mNumberOfAgents;
 };
 

dom/html/HTMLMediaElement.cpp

@@ -1198,6 +1198,7 @@ class HTMLMediaElement::AudioChannelAgentCallback final
     NotifyMediaStarted(mAudioChannelAgent->WindowID());
     WindowVolumeChanged(config.mVolume, config.mMuted);
     WindowSuspendChanged(config.mSuspend);
+    WindowAudioCaptureChanged(config.mCapturedAudio);
   }
 
   void StopAudioChanelAgent() {

dom/media/webaudio/AudioDestinationNode.cpp

@@ -630,6 +630,7 @@ void AudioDestinationNode::NotifyAudibleStateChanged(bool aAudible) {
 
   WindowVolumeChanged(config.mVolume, config.mMuted);
   WindowSuspendChanged(config.mSuspend);
+  WindowAudioCaptureChanged(config.mCapturedAudio);
 }
 
 }  // namespace dom