First step towards moving AudioDevice from content/ to media/audio.

media/audio/audio_device_ipc.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_DEVICE_IPC_H_
+#define MEDIA_AUDIO_AUDIO_DEVICE_IPC_H_
+
+#include "base/shared_memory.h"
+#include "base/sync_socket.h"
+#include "media/audio/audio_parameters.h"
+
+namespace media {
+
+// Current status of the audio output stream in the browser process. Browser
+// sends information about the current playback state and error to the
+// renderer process using this type.
+enum AudioStreamState {

[scherkus (not reviewing), 2012/07/23 22:57:51]

define inside Delegate as "State" and drop kAudioStream prefix?

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

Done.

+  kAudioStreamPlaying,
+  kAudioStreamPaused,
+  kAudioStreamError
+};
+
+class AudioDeviceIPCDelegate {

[scherkus (not reviewing), 2012/07/23 22:57:51]

any thoughts as to replacing this interface with two base::Bind() parameters?

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

I thought about that but decided not to do that right now for these reasons:

* Too many changes to the existing code.
* Registering/unregistering the callbacks can get more messy.  E.g. If an
AudioDevice implementation gets lazy and doesn't unregister, but rather null's a
callback, the AudioMessageFilter's callback vectors could fill up rather
quickly.
* It doesn't really give us more convenience over what we have currently and
generates more code.

Also, I was thinking about adding a callback to this interface, OnIPCClosed()
and make it a part of the contract that any cached references to the
AudioDeviceIPC object must be cleared at that point. WDYT?

+ public:
+

[scherkus (not reviewing), 2012/07/23 22:57:51]

remove blank line

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

Done.

+  // Called when state of an audio stream has changed in the browser process.

[scherkus (not reviewing), 2012/07/23 22:57:51]

nit: I'd drop the "in the browser process" bit -- browser vs renderer is a
src/content/ concept

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

Done.

+  virtual void OnStateChanged(AudioStreamState state) = 0;
+
+  // Called when an audio stream has been created in the browser process.

[scherkus (not reviewing), 2012/07/23 22:57:51]

ditto

[scherkus (not reviewing), 2012/07/23 22:57:51]

can we get docs on what these handles and params mean?

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

Done.

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

Done.

+  virtual void OnStreamCreated(base::SharedMemoryHandle handle,
+                               base::SyncSocket::Handle socket_handle,
+                               uint32 length) = 0;
+ protected:
+  virtual ~AudioDeviceIPCDelegate() {}

[scherkus (not reviewing), 2012/07/23 22:57:51]

even this it's OK to inline ctor/dtor in this particular instance, us media
folks have decided to avoid dealing with style exceptions and we impl the
ctor/dtor inside a .cc

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

ah, wasn't aware of that. Thanks for the heads up.

+};
+
+class AudioDeviceIPC {

[scherkus (not reviewing), 2012/07/23 22:57:51]

needs docs

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

Done.

+ public:
+  // Registers an AudioDeviceIPCDelegate and returns a stream_id that must

[scherkus (not reviewing), 2012/07/23 22:57:51]

|stream_id|

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

Done.

+  // be used with all other IPC functions in this interface.
+  virtual int AddDelegate(AudioDeviceIPCDelegate* sink) = 0;

[scherkus (not reviewing), 2012/07/23 22:57:51]

s/sink/delegate?

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

Done.

+
+  // Remove a delegate referenced by |stream_id| from the map.

[scherkus (not reviewing), 2012/07/23 22:57:51]

map? what map!? (update docs :))

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

Done.

+  virtual void RemoveDelegate(int stream_id) = 0;
+
+  virtual void CreateStream(int stream_id, const AudioParameters& params) = 0;

[scherkus (not reviewing), 2012/07/23 22:57:51]

docs?

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

Done.

+  virtual void PlayStream(int stream_id) = 0;
+  virtual void PauseStream(int stream_id) = 0;
+  virtual void FlushStream(int stream_id) = 0;
+  virtual void CloseStream(int stream_id) = 0;
+  virtual void SetVolume(int stream_id, double volume) = 0;
+
+ protected:
+  virtual ~AudioDeviceIPC() {}

[scherkus (not reviewing), 2012/07/23 22:57:51]

ditto

[tommi (sloooow) - chröme, 2012/07/24 09:49:44]

Done.

+};
+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_AUDIO_DEVICE_IPC_H_