Add WebThread in AudioDestination to support AudioWorkletThread

third_party/WebKit/Source/platform/audio/AudioDestination.h

Index: third_party/WebKit/Source/platform/audio/AudioDestination.h
diff --git a/third_party/WebKit/Source/platform/audio/AudioDestination.h b/third_party/WebKit/Source/platform/audio/AudioDestination.h
index fdb26dc8b2315a1ef8f7518ac1d4b744a8843979..8ae49569952671087644f157f73f6fdad416a328 100644
--- a/third_party/WebKit/Source/platform/audio/AudioDestination.h
+++ b/third_party/WebKit/Source/platform/audio/AudioDestination.h
@@ -43,6 +43,7 @@ namespace blink {
 class PushPullFIFO;
 class SecurityOrigin;
 class WebAudioLatencyHint;
+class WebThread;
 
 // The AudioDestination class is an audio sink interface between the media
 // renderer and the Blink's WebAudio module. It has a FIFO to adapt the
@@ -73,6 +74,11 @@ class PLATFORM_EXPORT AudioDestination : public WebAudioDevice::RenderCallback {
               double delayTimestamp,
               size_t priorFramesSkipped) override;
 
+  void requestRenderOnWebThread(size_t numberOfFrames,
+                                double delay,
+                                double delayTimestamp,
+                                size_t priorFramesSkipped);
+
   virtual void start();
   virtual void stop();
 
@@ -95,6 +101,9 @@ class PLATFORM_EXPORT AudioDestination : public WebAudioDevice::RenderCallback {
   size_t m_callbackBufferSize;
   bool m_isPlaying;
 
+  // WebThread for WebAudio rendering.
+  std::unique_ptr<WebThread> m_renderingThread;
+
   // The render callback function of WebAudio engine. (i.e. DestinationNode)
   AudioIOCallback& m_callback;