Support for AudioContextOptions latencyHint.

content/renderer/media/renderer_webaudiodevice_impl.h

Index: content/renderer/media/renderer_webaudiodevice_impl.h
diff --git a/content/renderer/media/renderer_webaudiodevice_impl.h b/content/renderer/media/renderer_webaudiodevice_impl.h
index a761e4294ee437024a979d1b6111b3e71b0b7cc6..a024345e1378aa830d21b4633bca7299ee7df2c2 100644
--- a/content/renderer/media/renderer_webaudiodevice_impl.h
+++ b/content/renderer/media/renderer_webaudiodevice_impl.h
@@ -13,6 +13,7 @@
 #include "media/base/audio_parameters.h"
 #include "media/base/audio_renderer_sink.h"
 #include "third_party/WebKit/public/platform/WebAudioDevice.h"
+#include "third_party/WebKit/public/platform/WebAudioLatencyHint.h"
 #include "third_party/WebKit/public/platform/WebVector.h"
 #include "url/origin.h"
 
@@ -25,7 +26,8 @@ class RendererWebAudioDeviceImpl
     : public blink::WebAudioDevice,
       public media::AudioRendererSink::RenderCallback {
  public:
-  RendererWebAudioDeviceImpl(const media::AudioParameters& params,
+  RendererWebAudioDeviceImpl(media::ChannelLayout layout,

[o1ka, 2016/12/02 12:02:12]

Would be great if we add unit tests for RendererWebAudioDeviceImpl as well

[Andrew MacPherson, 2016/12/05 14:12:52]

Sounds good! I will look into adding this in the next day or two.

[Andrew MacPherson, 2016/12/06 15:56:19]

olka@: I took a look into how the unit tests work and it looks like we'd need to
do a bit of refactoring in the RendererWebAudioDeviceImpl since it calls a
number of static methods (WebLocalFrame::frameForCurrentContext(),
AudioDeviceFactory::GetOutputDeviceInfo(),
AudioDeviceFactory::NewAudioRendererSink()) that I believe we'd need to mock.
This is no problem for me to do but I just wanted to double check that this is
what you intended before I start. Thanks! 

[o1ka, 2016/12/06 16:08:26]

Right. For AudioDeviceFactory and AudioRendererSink mocking you can take a look
at WebRtcAudioRendererTest
(https://cs.chromium.org/chromium/src/content/renderer/media/webrtc_audio_rend...).
And for frame id you can, for example, pass  FrameIdFromCurrentContext() as
callback into constructor (there are also other tricks to choose from).

[Andrew MacPherson, 2016/12/07 10:55:24]

Done, I've added a unit test to the WebAudioDeviceImpl that just verifies the
latency hint buffer sizes and does a simple start/stop test. I also added
callbacks as you suggested for the static method calls that were being used in
the constructor. Let me know if anything else is needed there!

+                             const blink::WebAudioLatencyHint& latency_hint,
                              blink::WebAudioDevice::RenderCallback* callback,
                              int session_id,
                              const url::Origin& security_origin);
@@ -35,6 +37,7 @@ class RendererWebAudioDeviceImpl
   void start() override;
   void stop() override;
   double sampleRate() override;
+  int framesPerBuffer() override;
 
   // AudioRendererSink::RenderCallback implementation.
   int Render(media::AudioBus* dest,
@@ -44,7 +47,9 @@ class RendererWebAudioDeviceImpl
   void OnRenderError() override;
 
  private:
-  const media::AudioParameters params_;
+  media::AudioParameters sink_params_;
+
+  const blink::WebAudioLatencyHint latency_hint_;
 
   // Weak reference to the callback into WebKit code.
   blink::WebAudioDevice::RenderCallback* const client_callback_;