Lazy initialization of the rendering thread in OfflineAudioContext

third_party/WebKit/Source/modules/webaudio/OfflineAudioDestinationNode.cpp

Index: third_party/WebKit/Source/modules/webaudio/OfflineAudioDestinationNode.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/OfflineAudioDestinationNode.cpp b/third_party/WebKit/Source/modules/webaudio/OfflineAudioDestinationNode.cpp
index e35b087652e1663a338b77707488110927f8aae1..32f1f5f2a9dd8b5195da38fbe02b435007eaf7aa 100644
--- a/third_party/WebKit/Source/modules/webaudio/OfflineAudioDestinationNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/OfflineAudioDestinationNode.cpp
@@ -46,8 +46,6 @@ OfflineAudioDestinationHandler::OfflineAudioDestinationHandler(
     AudioBuffer* render_target)
     : AudioDestinationHandler(node),
       render_target_(render_target),
-      render_thread_(
-          Platform::Current()->CreateThread("offline audio renderer")),
       frames_processed_(0),
       frames_to_process_(0),
       is_rendering_started_(false),
@@ -138,10 +136,10 @@ size_t OfflineAudioDestinationHandler::CallbackBufferSize() const {
   NOTREACHED();
   return 0;
 }
-WebThread* OfflineAudioDestinationHandler::OfflineRenderThread() {
-  DCHECK(render_thread_);
 
-  return render_thread_.get();
+void OfflineAudioDestinationHandler::InitializeOfflineRenderThread() {
+  DCHECK(IsMainThread());
+  render_thread_ = Platform::Current()->CreateThread("offline audio renderer");
 }
 
 void OfflineAudioDestinationHandler::StartOfflineRendering() {
@@ -253,6 +251,11 @@ void OfflineAudioDestinationHandler::NotifySuspend(size_t frame) {
 }
 
 void OfflineAudioDestinationHandler::NotifyComplete() {
+  DCHECK(IsMainThread());
+
+  // Nullify the rendering thread to save the system resource.
+  render_thread_.reset();
+
   // The OfflineAudioContext might be gone.
   if (Context())
     Context()->FireCompletionEvent();