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..423a588ee4519e1b26295eb69422babd01a983da 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),
@@ -104,12 +102,14 @@ unsigned long OfflineAudioDestinationHandler::MaxChannelCount() const {
 
 void OfflineAudioDestinationHandler::StartRendering() {
   DCHECK(IsMainThread());
-  DCHECK(render_thread_);
   DCHECK(render_target_);
 
   if (!render_target_)
     return;
 
+  render_thread_ = Platform::Current()->CreateThread("offline audio renderer");

[Raymond Toy, 2017/05/19 19:37:54]

Maybe if we fail to create the thread we can reject the promise?  Can't see
anything in the spec about this, but it makes sense since promise always have a
resolve and a reject.

+  DCHECK(render_thread_);
+
   // Rendering was not started. Starting now.
   if (!is_rendering_started_) {
     is_rendering_started_ = true;