Remove the AudioManager singleton.

media/audio/audio_output_dispatcher.h

 // Copyright (c) 2011 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.
 
-// AudioOutputDispatcher dispatches creation and deletion of audio
-// output streams. AudioOutputProxy objects use this class to allocate
-// and recycle actual audio output streams. When playback is started,
-// the proxy calls StreamStarted() to get an output stream that it
-// uses to play the sound. When playback is stopped, the proxy returns
-// the stream back to the dispatcher by calling StreamStopped().
+// AudioOutputDispatcher is a single-threaded class that dispatches creation and
+// deletion of audio output streams. AudioOutputProxy objects use this class to
+// allocate and recycle actual audio output streams. When playback is started,
+// the proxy calls StreamStarted() to get an output stream that it uses to play
+// audio. When playback is stopped, the proxy returns the stream back to the
+// dispatcher by calling StreamStopped().
 //
-// To avoid opening and closing audio devices more frequently than it
-// is neccessary, each dispatcher has a pool of inactive physical
-// streams. A stream is closed only if it hasn't been used for a
-// certain period of time (specified in the constructor).
+// To avoid opening and closing audio devices more frequently than necessary,
+// each dispatcher has a pool of inactive physical streams. A stream is closed
+// only if it hasn't been used for a certain period of time (specified via the
+// constructor).
 //
-// AudioManagerBase creates one AudioOutputDispatcher per each
-// possible set of audio parameters, i.e. streams with different
-// parameters are managed independently.
+// AudioManagerBase creates one AudioOutputDispatcher on the audio thread for
+// each possible set of audio parameters. I.e streams with different parameters
+// are managed independently.  The AudioOutputDispatcher instance is then
+// deleted on the audio thread when the AudioManager shuts down.
 
 #ifndef MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_H_
 #define MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_H_
 
 #include <vector>
 #include <list>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/timer.h"
 #include "media/audio/audio_manager.h"
 #include "media/audio/audio_parameters.h"
 
 class AudioOutputStream;
 class MessageLoop;
 
 class MEDIA_EXPORT AudioOutputDispatcher
     : public base::RefCountedThreadSafe<AudioOutputDispatcher> {
  public:
@@ skipping 18 matching lines @@
 
   // Called by AudioOutputProxy when the stream is stopped.  Holds the
   // stream temporarily in |pausing_streams_| and then |stream| is
   // added to the pool of pending streams (i.e. |idle_streams_|).
   // Ownership of the |stream| is passed to the dispatcher.
   void StreamStopped(AudioOutputStream* stream);
 
   // Called by AudioOutputProxy when the stream is closed.
   void StreamClosed();
 
+  // Called on the audio thread when the AudioManager is shutting down.
+  void Shutdown();
+
   MessageLoop* message_loop();
 
  private:
   friend class AudioOutputProxyTest;
 
   // Creates a new physical output stream, opens it and pushes to
   // |idle_streams_|.  Returns false if the stream couldn't be created or
   // opened.
   bool CreateAndOpenStream();
 
   // A task scheduled by StreamStarted(). Opens a new stream and puts
   // it in |idle_streams_|.
   void OpenTask();
 
   // Before a stream is reused, it should sit idle for a bit.  This task is
   // called once that time has elapsed.
   void StopStreamTask();
 
   // Called by |close_timer_|. Closes all pending stream.
   void ClosePendingStreams();
 
+  // A no-reference-held pointer (we don't want circular references) back to the
+  // AudioManager that owns this object.
   AudioManager* audio_manager_;
   MessageLoop* message_loop_;
   AudioParameters params_;
 
   int64 pause_delay_milliseconds_;
   size_t paused_proxies_;
-  std::vector<AudioOutputStream*> idle_streams_;
-  std::list<AudioOutputStream*> pausing_streams_;
+  typedef std::list<AudioOutputStream*> AudioOutputStreamList;
+  AudioOutputStreamList idle_streams_;
+  AudioOutputStreamList pausing_streams_;
+
+  // Used to post delayed tasks to ourselves that we cancel inside Shutdown().
+  base::WeakPtrFactory<AudioOutputDispatcher> weak_this_;
   base::DelayTimer<AudioOutputDispatcher> close_timer_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioOutputDispatcher);
 };
 
 #endif  // MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_H_