Stop source and fire MediaStreamTrack ended event if missing audio input callbacks are detected.

content/renderer/media/webrtc/processed_local_audio_source.h

Index: content/renderer/media/webrtc/processed_local_audio_source.h
diff --git a/content/renderer/media/webrtc/processed_local_audio_source.h b/content/renderer/media/webrtc/processed_local_audio_source.h
index dead7afa75b877f1e926f5d82c9cfb855521e465..598e9a388c7cc2d89ca500dec684bc1bae3623d1 100644
--- a/content/renderer/media/webrtc/processed_local_audio_source.h
+++ b/content/renderer/media/webrtc/processed_local_audio_source.h
@@ -16,6 +16,8 @@
 #include "media/base/audio_capturer_source.h"
 #include "third_party/WebKit/public/platform/WebMediaConstraints.h"
 
+#include "base/timer/timer.h"
+
 namespace media {
 class AudioBus;
 }
@@ -101,6 +103,8 @@ class CONTENT_EXPORT ProcessedLocalAudioSource final
   // processing will take place.
   int GetBufferSize(int sample_rate) const;
 
+  void CheckIfInputStreamIsAlive();
+
   // The RenderFrame that will consume the audio data. Used when creating
   // AudioCapturerSources.
   const int consumer_render_frame_id_;
@@ -136,6 +140,10 @@ class CONTENT_EXPORT ProcessedLocalAudioSource final
 
   bool allow_invalid_render_frame_id_for_testing_;
 
+  base::RepeatingTimer check_alive_timer_;
+  base::subtle::Atomic32 input_callback_is_active_;
+  base::TimeTicks last_callback_time_;
+
   DISALLOW_COPY_AND_ASSIGN(ProcessedLocalAudioSource);
 };