Implement two new policies to control muting the audio I/O.

chrome/browser/chromeos/audio/audio_mixer_cras.h

Index: chrome/browser/chromeos/audio/audio_mixer_cras.h
diff --git a/chrome/browser/chromeos/audio/audio_mixer_cras.h b/chrome/browser/chromeos/audio/audio_mixer_cras.h
index ef002abc8230e32e3db65fb68bcda3f39d403d34..5650fb0cfd6ccc7a7135f4ae03329e5a6a95a43e 100644
--- a/chrome/browser/chromeos/audio/audio_mixer_cras.h
+++ b/chrome/browser/chromeos/audio/audio_mixer_cras.h
@@ -29,7 +29,13 @@ class AudioMixerCras : public AudioMixer {
   virtual double GetVolumePercent() OVERRIDE;
   virtual void SetVolumePercent(double percent) OVERRIDE;
   virtual bool IsMuted() OVERRIDE;
-  virtual void SetMuted(bool muted) OVERRIDE;
+  virtual void SetMuted(bool mute) OVERRIDE;
+  virtual bool IsMuteLocked() OVERRIDE;
+  virtual void SetMuteLocked(bool locked) OVERRIDE;
+  virtual bool IsCaptureMuted() OVERRIDE;
+  virtual void SetCaptureMuted(bool mute) OVERRIDE;
+  virtual bool IsCaptureMuteLocked() OVERRIDE;
+  virtual void SetCaptureMuteLocked(bool locked) OVERRIDE;
 
  private:
   // Tries to connect to CRAS.  On failure, posts a delayed Connect() task to
@@ -40,6 +46,10 @@ class AudioMixerCras : public AudioMixer {
   // |is_muted_|. No-op if not connected.
   void ApplyState();
 
+  // Calls ApplyState on the proper thread only if no other call is currently
+  // pending.
+  void ApplyStateIfNeeded();
+
   // Interfaces to the audio server.
   struct cras_client *client_;
 
@@ -53,6 +63,9 @@ class AudioMixerCras : public AudioMixer {
 
   // Most recently-requested muting state.
   bool is_muted_;
+  bool is_mute_locked_;
+  bool is_capture_muted_;
+  bool is_capture_mute_locked_;
 
   // Is there already a pending call to ApplyState() scheduled on |thread_|?
   bool apply_is_pending_;
@@ -60,7 +73,8 @@ class AudioMixerCras : public AudioMixer {
   // Background thread used for interacting with CRAS.
   scoped_ptr<base::Thread> thread_;
 
-  // Guards |volume_percent_|, |is_muted_|, and |apply_is_pending_|.
+  // Guards |volume_percent_|, |is_muted_|, |is_mute_locked_|,
+  // |is_capture_muted_|, |is_capture_mute_locked_|, and |apply_is_pending_|.
   base::Lock lock_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioMixerCras);