MediaCaptureFromElement: add support for audio captureStream().

media/blink/webaudiosourceprovider_impl.h

 // Copyright 2013 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_BLINK_WEBAUDIOSOURCEPROVIDER_IMPL_H_
 #define MEDIA_BLINK_WEBAUDIOSOURCEPROVIDER_IMPL_H_
 
 #include <stddef.h>
 
 #include <string>
@@ skipping 54 matching lines @@
   void Initialize(const AudioParameters& params,
                   RenderCallback* renderer) override;
   void SwitchOutputDevice(const std::string& device_id,
                           const url::Origin& security_origin,
                           const OutputDeviceStatusCB& callback) override;
 
   // These methods allow a client to get a copy of the rendered audio.
   void SetCopyAudioCallback(const CopyAudioCB& callback);
   void ClearCopyAudioCallback();
 
+  base::WeakPtr<WebAudioSourceProviderImpl> AsWeakPtr() {
+    return weak_factory_.GetWeakPtr();
+  }
+
+  int RenderForTesting(AudioBus* audio_bus);

[miu, 2016/05/19 22:44:30]

Not sure you should have made this public. Instead, could your test code just
call provideInput()?

[mcasas, 2016/05/19 23:57:55]

provideInput() is only available for the render-to-WebAudio
path: WASPImpl can only pass audio onwards to either
|renderer_| or |client_|, but not both. provideAudio() is 
used by the second path (hence the check in [1]). I could
modify the unittests to use this particular path, but IMHO
is not worth it. (Also I can't easily make me friend of this
class because HTMLAudioElementCapturerSourceTest is
in content/, argh!).

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/media/blink/webaud...

+
  private:
   friend class WebAudioSourceProviderImplTest;
   ~WebAudioSourceProviderImpl() override;
 
   // Calls setFormat() on |client_| from the Blink renderer thread.
   void OnSetFormat();
 
-  int RenderForTesting(AudioBus* audio_bus);
-
   // Used to keep the volume across reconfigurations.
   double volume_;
 
   // Tracks the current playback state.
   enum PlaybackState { kStopped, kStarted, kPlaying };
   PlaybackState state_;
 
   // Closure that calls OnSetFormat() on |client_| on the renderer thread.
   base::Closure set_format_cb_;
   // When set via setClient() it overrides |sink_| for consuming audio.
@@ skipping 10 matching lines @@
 
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<WebAudioSourceProviderImpl> weak_factory_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(WebAudioSourceProviderImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BLINK_WEBAUDIOSOURCEPROVIDER_IMPL_H_