Implement AudioOutputProxy.

media/audio/audio_output_dispatcher.h

+// Copyright (c) 2010 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_OUTPUT_DISPATCHER_H_
+#define MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/ref_counted.h"
+#include "base/time.h"
+#include "media/audio/audio_manager.h"
+#include "media/audio/audio_parameters.h"
+
+class AudioOutputStream;
+class MessageLoop;
+
+// AudioOutputDispatcher dispatches creation and deletion of audio
+// output streams. AudioManagerBase creates one AudioOutputDispatcher
+// per each possible set of audio parameters. AudioOutputProxy
+// objects use this class to allocate and recycle actual audio output
+// streams.
+class AudioOutputDispatcher
+    : public base::RefCountedThreadSafe<AudioOutputDispatcher> {
+ public:
+  AudioOutputDispatcher(AudioManager* audio_manager,
+                        const AudioParameters& params);
+  ~AudioOutputDispatcher();

[scherkus (not reviewing), 2010/11/22 06:43:15]

virtual

[Sergey Ulanov, 2010/11/23 19:51:46]

Nobody inherits from this class, and there are no virtual methods, so destructor
doesn't need to be virtual.

+
+  // Following 4 methods are called by AudioOutput when a stream

[scherkus (not reviewing), 2010/11/22 06:43:15]

Might be wrong here.. but do you meant AudioOutputProxy instead of AudioOutput
here?

[Sergey Ulanov, 2010/11/23 19:51:46]

Done.

+  // is opened, started, stopped or closed.
+  bool StreamOpened();
+  AudioOutputStream* StreamStarted();
+  void StreamStopped(AudioOutputStream* stream);

[scherkus (not reviewing), 2010/11/22 06:43:15]

I think we need some comments for these functions as reading through the code
they have some not-so-obvious logic + return values

[Sergey Ulanov, 2010/11/23 19:51:46]

Done.

+  void StreamClosed();
+
+  MessageLoop* message_loop();
+
+  void set_close_delay(base::TimeDelta delay);

[scherkus (not reviewing), 2010/11/22 06:43:15]

is this only used for tests?

consider using FRIEND_TEST() or passing this in via constructor

[Sergey Ulanov, 2010/11/23 19:51:46]

Yes.
Move this to constructor

+
+ private:
+  friend class AudioOutputProxyTest;
+
+  AudioOutputStream* CreateAndOpenStream();
+  void ScheduleCloseTask();
+  void OpenTask();
+  void CloseTask();
+  void ClosePendingStreams();
+
+  AudioManager* audio_manager_;
+  MessageLoop* message_loop_;
+  AudioParameters params_;
+  base::TimeDelta close_delay_;
+
+  int paused_proxies_;
+  std::vector<AudioOutputStream*> streams_;
+  base::Time last_activity_time_;

[scherkus (not reviewing), 2010/11/22 06:43:15]

I think you can replace a bunch of this last_activity_time_ + close_delay_ +
close_task_scheduled_ stuff with DelayTimer from base/timer.h

I'd encourage you to check that out + other helper classes to see if we can
avoid having complicated timing logic baked into this class

[Sergey Ulanov, 2010/11/23 19:51:46]

Wow, that is fantastic. I didn't know about it. Yes, DelayTimer works for this
scenario. Thanks for suggesting it!

+  bool close_task_scheduled_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioOutputDispatcher);
+};
+
+#endif  // MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_H_