Detect AudioInputStream muting and propagate to MediaStreamAudioSource.

media/audio/fake_audio_input_stream.cc

Index: media/audio/fake_audio_input_stream.cc
diff --git a/media/audio/fake_audio_input_stream.cc b/media/audio/fake_audio_input_stream.cc
index 52d7218d2870da974913803fe97a1989f290f4e3..188d05c7fb131def740fb0c86322545735e924fd 100644
--- a/media/audio/fake_audio_input_stream.cc
+++ b/media/audio/fake_audio_input_stream.cc
@@ -4,6 +4,7 @@
 
 #include "media/audio/fake_audio_input_stream.h"
 
+#include "base/atomicops.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
@@ -19,6 +20,10 @@
 
 namespace media {
 
+namespace {
+base::subtle::AtomicWord g_fake_input_streams_are_muted = 0;
+}
+
 AudioInputStream* FakeAudioInputStream::MakeFakeStream(
     AudioManagerBase* manager,
     const AudioParameters& params) {
@@ -81,7 +86,7 @@ double FakeAudioInputStream::GetVolume() {
 
 bool FakeAudioInputStream::IsMuted() {
   DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
-  return false;
+  return base::subtle::NoBarrier_Load(&g_fake_input_streams_are_muted) != 0;

[dcheng, 2017/06/17 08:50:02]

Is it necessary to use atomics here?

The code would be easier to understand without it.

 }
 
 bool FakeAudioInputStream::SetAutomaticGainControl(bool enabled) {
@@ -136,4 +141,9 @@ void FakeAudioInputStream::BeepOnce() {
   BeepingSource::BeepOnce();
 }
 
+void FakeAudioInputStream::SetGlobalMutedState(bool is_muted) {
+  base::subtle::NoBarrier_Store(&g_fake_input_streams_are_muted,
+                                (is_muted ? 1 : 0));
+}
+
 }  // namespace media