Refactor AudioInputController and related interfaces.

media/audio/audio_io.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.
 
 #ifndef MEDIA_AUDIO_AUDIO_IO_H_
 #define MEDIA_AUDIO_AUDIO_IO_H_
 
 #include <stdint.h>
 
 #include "base/time/time.h"
@@ skipping 76 matching lines @@
   // must always be followed by a call to Close() even if Open() fails.
   virtual bool Open() = 0;
 
   // Starts playing audio and generating AudioSourceCallback::OnMoreData().
   // Since implementor of AudioOutputStream may have internal buffers, right
   // after calling this method initial buffers are fetched.
   //
   // The output stream does not take ownership of this callback.
   virtual void Start(AudioSourceCallback* callback) = 0;
 
-  // Stops playing audio. Effect might not be instantaneous as the hardware
-  // might have locked audio data that is processing.
+  // Stops playing audio.  The operation completes synchronously meaning that
+  // once Stop() has completed executing, no further callbacks will be made to
+  // the callback object that was supplied to Start() and it can be safely
+  // deleted.
   virtual void Stop() = 0;
 
   // Sets the relative volume, with range [0.0, 1.0] inclusive.
   virtual void SetVolume(double volume) = 0;
 
   // Gets the relative volume, with range [0.0, 1.0] inclusive.
   virtual void GetVolume(double* volume) = 0;
 
   // Close the stream. This also generates AudioSourceCallback::OnClose().
   // After calling this method, the object should not be used anymore.
@@ skipping 66 matching lines @@
   // Returns the Automatic Gain Control (AGC) state.
   virtual bool GetAutomaticGainControl() = 0;
 
   // Returns the current muting state for the microphone.
   virtual bool IsMuted() = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_IO_H_