Fix getUserMedia so that failure is reported for invalid audio sources.

content/renderer/media/local_media_stream_audio_source.h

 // Copyright 2016 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.
 
 #ifndef CONTENT_RENDERER_MEDIA_LOCAL_MEDIA_STREAM_AUDIO_SOURCE_H_
 #define CONTENT_RENDERER_MEDIA_LOCAL_MEDIA_STREAM_AUDIO_SOURCE_H_
 
 #include "content/renderer/media/media_stream_audio_source.h"
 #include "media/base/audio_capturer_source.h"
 
 namespace content {
 
 // Represents a local source of audio data generated by an AudioInputDevice.
 // Uses content::AudioDeviceFactory to auto-create the AudioInputDevice, using
 // the parameters and session ID found in StreamDeviceInfo, just before the
 // first track is connected. Audio data is transported directly to the tracks
 // (i.e., there is no audio processing).
 class CONTENT_EXPORT LocalMediaStreamAudioSource
     : NON_EXPORTED_BASE(public MediaStreamAudioSource),
       NON_EXPORTED_BASE(public media::AudioCapturerSource::CaptureCallback) {
  public:
   // |consumer_render_frame_id| references the RenderFrame that will consume the
   // audio data. Audio parameters and (optionally) a pre-existing audio session
   // ID are read from |device_info|.
   LocalMediaStreamAudioSource(int consumer_render_frame_id,
-                              const StreamDeviceInfo& device_info);
+                              const StreamDeviceInfo& device_info,
+                              const ConstraintsCallback& started_callback);
 
   ~LocalMediaStreamAudioSource() final;
 
  private:
   // MediaStreamAudioSource implementation.
   bool EnsureSourceIsStarted() final;
   void EnsureSourceIsStopped() final;
 
   // media::AudioCapturerSource::CaptureCallback implementation.
+  void OnCaptureStarted() final;
   void Capture(const media::AudioBus* audio_bus,
                int audio_delay_milliseconds,
                double volume,
                bool key_pressed) final;
   void OnCaptureError(const std::string& message) final;
 
   // The RenderFrame that will consume the audio data. Used when creating
   // AudioInputDevices via the AudioDeviceFactory.
   const int consumer_render_frame_id_;
 
   // The device created by the AudioDeviceFactory in EnsureSourceIsStarted().
   scoped_refptr<media::AudioCapturerSource> source_;
 
+  // Callback that's called when the audio source has been initialized.
+  ConstraintsCallback started_callback_;
+
   // In debug builds, check that all methods that could cause object graph
   // or data flow changes are being called on the main thread.
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(LocalMediaStreamAudioSource);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_LOCAL_MEDIA_STREAM_AUDIO_SOURCE_H_