Support for AudioContextOptions latencyHint.

third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.h

Index: third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.h
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.h b/third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.h
index dc7fe45b785aa4c552a80638aed3a35d425c3ec1..9054ba8589499705fbbbb9070bcddee20364fba2 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.h
@@ -39,7 +39,7 @@ class BaseAudioContext;
 
 class AudioDestinationHandler : public AudioHandler, public AudioIOCallback {
  public:
-  AudioDestinationHandler(AudioNode&, float sampleRate);
+  AudioDestinationHandler(AudioNode&);
   ~AudioDestinationHandler() override;
 
   // AudioHandler
@@ -65,6 +65,12 @@ class AudioDestinationHandler : public AudioHandler, public AudioIOCallback {
   virtual void startRendering() = 0;
   virtual void stopRendering() = 0;
 
+  virtual double sampleRate() const = 0;
+
+  // Returns the audio buffer size in frames used by the underlying audio
+  // hardware.

[Raymond Toy, 2016/12/08 17:14:38]

This isn't the size of the underlying audio hardware is it? Isn't it the buffer
size for the AudioContext, which is related to the audio hardware size, but not
necessary equal to it.

[Andrew MacPherson, 2016/12/09 12:34:14]

Makes sense, I've updated it now.

+  virtual int framesPerBuffer() const = 0;
+
  protected:
   // LocalAudioInputProvider allows us to expose an AudioSourceProvider for
   // local/live audio input.  If there is local/live audio input, we call set()