Adds AudioDevice factory for all audio clients in Chrome

content/renderer/media/audio_message_filter.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.
 //
 // MessageFilter that handles audio messages and delegates them to audio
 // renderers. Created on render thread, AudioMessageFilter is operated on
 // IO thread (secondary thread of render process) it intercepts audio messages
 // and process them on IO thread since these messages are time critical.
 
 #ifndef CONTENT_RENDERER_MEDIA_AUDIO_MESSAGE_FILTER_H_
@@ skipping 21 matching lines @@
     virtual void OnStreamCreated(base::SharedMemoryHandle handle,
                                  base::SyncSocket::Handle socket_handle,
                                  uint32 length) = 0;
 
    protected:
     virtual ~Delegate() {}
   };
 
   AudioMessageFilter();
 
+  // Getter for the one AudioMessageFilter object.
+  static AudioMessageFilter* current();

[jam, 2012/06/27 15:56:29]

per style guide, since the implementation is in the cc file this should be
CamelCase, i.e. Get(). The current() naming for RenderThread where I assume you
got this is incorrect (it was a holdover from when it was inlined) and just
needs to update all the code.

[henrika (OOO until Aug 14), 2012/06/27 17:54:47]

Got it. Not GetCurrent() then?

[jam, 2012/06/27 18:03:58]

current() was named like because initially there was a thought that there would
be different RenderThread objects in the same renderer process, so current()
would give the current one for the given thread. but that never panned out.

Get() is more consistent with getters

[henrika (OOO until Aug 14), 2012/06/28 11:36:01]

Done.

+
   // Add a delegate to the map and return id of the entry.
   int32 AddDelegate(Delegate* delegate);
 
   // Remove a delegate referenced by |id| from the map.
   void RemoveDelegate(int32 id);
 
   // Sends an IPC message using |channel_|.
   bool Send(IPC::Message* message);
 
   // IPC::ChannelProxy::MessageFilter override. Called on IO thread.
@@ skipping 16 matching lines @@
 #else
                        base::FileDescriptor socket_descriptor,
 #endif
                        uint32 length);
 
 
   // Received when internal state of browser process' audio output device has
   // changed.
   void OnStreamStateChanged(int stream_id, AudioStreamState state);
 
+  // The singleton instance for this filter.
+  // Should only be accessed on the main renderer thread.

[jam, 2012/06/27 15:56:29]

nit: i thought the whole point of exposing the getter above is that it'll called
on multiple threads?

[henrika (OOO until Aug 14), 2012/06/27 17:54:47]

I do need a vacation. Thanks.

[henrika (OOO until Aug 14), 2012/06/28 11:36:01]

Done.

+  static AudioMessageFilter* filter_;
+
   // A map of stream ids to delegates.
   IDMap<Delegate> delegates_;
 
   IPC::Channel* channel_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioMessageFilter);
 };
 
 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_MESSAGE_FILTER_H_