Tab Audio Mirroring: WebContentsAudioInputStream is a new implementation which represents the lifet…

media/audio/virtual_audio_input_stream.h

Index: media/audio/virtual_audio_input_stream.h
diff --git a/media/audio/virtual_audio_input_stream.h b/media/audio/virtual_audio_input_stream.h
index fcb87a4db10bd58955a988f492ee6fa4ff7cf5d1..635a781a30dcba1550fc46907ea67a8342b74855 100644
--- a/media/audio/virtual_audio_input_stream.h
+++ b/media/audio/virtual_audio_input_stream.h
@@ -12,10 +12,13 @@
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "media/audio/audio_io.h"
-#include "media/audio/audio_manager_base.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/audio_converter.h"
 
+namespace base {
+class MessageLoopProxy;
+}
+
 namespace media {
 
 class LoopbackAudioConverter;
@@ -26,10 +29,16 @@ class VirtualAudioOutputStream;
 // audio until this VirtualAudioInputStream is stopped and closed.
 class MEDIA_EXPORT VirtualAudioInputStream : public AudioInputStream {
  public:
-  static VirtualAudioInputStream* MakeStream(
-      AudioManagerBase* manager,
-      const AudioParameters& params,
-      base::MessageLoopProxy* message_loop);
+  // Callback invoked just after VirtualAudioInputStream is closed.  It is safe
+  // for the callback to delete this.
+  typedef base::Callback<void(VirtualAudioInputStream* vais)>

[DaleCurtis, 2013/01/17 01:15:52]

I think "It is safe for the callback to delete this." needs elaboration. Given
the current usage pattern, it seems required to delete this object?

[miu, 2013/01/17 05:33:55]

I took out the "safe to delete this" text.  It's actually irrelevant since it's
up to the owner of the object whether it wants to delete it upon close or at
some later time:

AudioManagerBase: The callback runs a method that forces all outstanding VAOS
objects to be closed (via the device change mechanism) and then deletes VAIS.

WebContentsAudioInputStream: The callback is unused.  VAIS is deleted via
scoped_ptr in the WCAIS::Impl class.  The reason for this is that there's no way
to synchronously force-close all associated VAOS objects: The path between WCAIS
and AudioOutputController must go through AudioMirroringManager and
AudioRendererHost, which live on the IO thread.  Each VAOS object created by
WCAIS::Impl holds a ref on WCAIS::Impl to make sure VAIS outlives all the VAOS
objects.

+      AfterCloseCallback;
+
+  // Construct a target for audio loopback which mixes multiple data streams
+  // into a single stream having the given |params|.
+  VirtualAudioInputStream(const AudioParameters& params,
+                          base::MessageLoopProxy* message_loop,
+                          const AfterCloseCallback& after_close_cb);
 
   virtual ~VirtualAudioInputStream();
 
@@ -55,28 +64,24 @@ class MEDIA_EXPORT VirtualAudioInputStream : public AudioInputStream {
   virtual void RemoveOutputStream(VirtualAudioOutputStream* stream,
                                   const AudioParameters& output_params);
 
- protected:
+ private:
   friend class VirtualAudioInputStreamTest;
-  FRIEND_TEST_ALL_PREFIXES(AudioOutputControllerTest,
-                           VirtualStreamsTriggerDeviceChange);
 
   typedef std::map<AudioParameters, LoopbackAudioConverter*> AudioConvertersMap;
 
-  VirtualAudioInputStream(AudioManagerBase* manager,
-                          const AudioParameters& params,
-                          base::MessageLoopProxy* message_loop);
-
   // When Start() is called on this class, we continuously schedule this
   // callback to render audio using any attached VirtualAudioOutputStreams until
   // Stop() is called.
   void ReadAudio();
 
-  AudioManagerBase* audio_manager_;
-  base::MessageLoopProxy* message_loop_;
+  base::MessageLoopProxy* const message_loop_;
+
+  AfterCloseCallback after_close_cb_;
+
   AudioInputCallback* callback_;
 
   // Non-const for testing.
-  base::TimeDelta buffer_duration_ms_;
+  base::TimeDelta buffer_duration_;
   scoped_array<uint8> buffer_;
   AudioParameters params_;
   scoped_ptr<AudioBus> audio_bus_;
@@ -91,7 +96,7 @@ class MEDIA_EXPORT VirtualAudioInputStream : public AudioInputStream {
   AudioConverter mixer_;
 
   // Number of currently attached VirtualAudioOutputStreams.
-  int num_attached_outputs_streams_;
+  int num_attached_output_streams_;
 
   DISALLOW_COPY_AND_ASSIGN(VirtualAudioInputStream);
 };