Propagate muted state from MediaStreamAudioSource into JS.

media/audio/fake_audio_input_stream.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // A fake implementation of AudioInputStream, useful for testing purpose.
 
 #ifndef MEDIA_AUDIO_FAKE_AUDIO_INPUT_STREAM_H_
 #define MEDIA_AUDIO_FAKE_AUDIO_INPUT_STREAM_H_
 
 #include <memory>
@@ skipping 36 matching lines @@
   // FakeVideoCaptureDevice is disconnected from an audio device. This means
   // only one instance of this class gets to respond, which is okay because we
   // assume there's only one stream for this testing purpose. Furthermore this
   // method will do nothing if --use-file-for-fake-audio-capture is specified
   // since the input stream will be playing from a file instead of beeping.
   // TODO(hclam): Make this non-static. To do this we'll need to fix
   // crbug.com/159053 such that video capture device is aware of audio
   // input stream.
   static void BeepOnce();
 
+  // Set the muted state for _all_ FakeAudioInputStreams. The value is global,
+  // so it can be set before any FakeAudioInputStreams have been created.
+  static void SetMutedState(bool is_muted);

[ossu-chromium, 2017/06/07 17:20:45]

Initially, I thought having SetMutedState be static was a bit hacky. Considering
we want to be able to set the muted state _before_ any stream is constructed, to
check initial conditions, I now think it's as good as can be.

+
  private:
   FakeAudioInputStream(AudioManagerBase* manager,
                        const AudioParameters& params);
   ~FakeAudioInputStream() override;
 
   std::unique_ptr<AudioOutputStream::AudioSourceCallback> ChooseSource();
   void ReadAudioFromSource();
 
   AudioManagerBase* audio_manager_;
   AudioInputCallback* callback_;
   FakeAudioWorker fake_audio_worker_;
   AudioParameters params_;
 
   std::unique_ptr<AudioOutputStream::AudioSourceCallback> audio_source_;
   std::unique_ptr<media::AudioBus> audio_bus_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeAudioInputStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_FAKE_AUDIO_INPUT_STREAM_H_