Detect AudioInputStream muting and propagate to MediaStreamAudioSource.

media/audio/audio_input_controller.cc

Index: media/audio/audio_input_controller.cc
diff --git a/media/audio/audio_input_controller.cc b/media/audio/audio_input_controller.cc
index 5c8997e0875b0853d02152b2c2d1ab6531f487ef..017ba18198f42acec130681ba3c0ffba607fd3c8 100644
--- a/media/audio/audio_input_controller.cc
+++ b/media/audio/audio_input_controller.cc
@@ -26,6 +26,7 @@ namespace media {
 namespace {
 
 const int kMaxInputChannels = 3;
+constexpr int kCheckMutedStateIntervalSeconds = 1;
 
 #if defined(AUDIO_POWER_MONITORING)
 // Time in seconds between two successive measurements of audio power levels.
@@ -353,6 +354,15 @@ void AudioInputController::DoCreateForStream(
   // Finally, keep the stream pointer around, update the state and notify.
   stream_ = stream_to_control;
   handler_->OnCreated(this);
+
+  // Check the current muted state and start a repeating timer to keep that
+  // updated.
+  CheckMutedState();
+  check_muted_state_timer_.reset(new base::RepeatingTimer());

[Max Morin, 2017/06/02 09:56:04]

If you use unique_ptr, most Chromium people prefer base::MakeUnique over raw new
calls for allocating memory. Up to you though.

[Guido Urdaneta, 2017/06/02 13:33:45]

MakeUnique is strongly preferred over raw new, but you can alsop switch to a
regular object.

+  check_muted_state_timer_->Start(
+      FROM_HERE, base::TimeDelta::FromSeconds(kCheckMutedStateIntervalSeconds),
+      this, &AudioInputController::CheckMutedState);
+  DCHECK(check_muted_state_timer_->IsRunning());
 }
 
 void AudioInputController::DoRecord() {
@@ -382,6 +392,13 @@ void AudioInputController::DoClose() {
   if (!stream_)
     return;
 
+  // Stop the muted check timer.
+  // TODO(ossu): Can't we just reset() it here? Should stop automatically, IIUC.

[Max Morin, 2017/06/02 09:56:04]

Looking at the implementation, yes. Would be nice to have that documented in
timer.h if you want to use it, though.

[ossu-chromium, 2017/06/02 10:48:00]

The top of timer.h says:
"OneShotTimer and RepeatingTimer both cancel the timer when they go out of
scope, which makes it easy to ensure that you do not get called when your object
has gone out of scope."

But this is how we've used it elsewhere. Looking at it again, I'm not sure why
we recreate the timer at all. Can it not just be a member variable and
started/stopped on Create() and Close()?

[Guido Urdaneta, 2017/06/02 13:33:45]

There are also many uses in the codebase that just call reset() without calling
Stop().

+  if (check_muted_state_timer_ != nullptr) {
+    check_muted_state_timer_->Stop();
+    check_muted_state_timer_.reset();
+  }
+
   // Allow calling unconditionally and bail if we don't have a stream to close.
   if (audio_callback_) {
     stream_->Stop();
@@ -652,6 +669,17 @@ bool AudioInputController::CheckAudioPower(const AudioBus* source,
 #endif
 }
 
+void AudioInputController::CheckMutedState() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  DCHECK(stream_);
+  const bool new_state = stream_->IsMuted();
+  if (new_state != is_muted_) {
+    is_muted_ = new_state;
+    // Don't log this here, AudioInputRendererHost will log instead.

[Max Morin, 2017/06/02 09:56:04]

Does AIRH actually log this?

[ossu-chromium, 2017/06/02 10:48:00]

Aww, shucks. It did until I removed that. I think that, since we're delegating
the logging to that class anyways, we might as well log this there directly,
rather than imposing a second PostTask etc. just to get the message out. Will
add it back in in AIRH::DoNotifyMutedState.

+    handler_->OnMuted(this, is_muted_);
+  }
+}
+
 // static
 AudioInputController::StreamType AudioInputController::ParamsToStreamType(
     const AudioParameters& params) {