scheduler: Tell v8 about the current RAIL mode

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index ed37e5ebe2b5cd39365a554dd33d38ee8d1fceaa..189326e22f365dda8856dec3faaa9876a4940761 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -441,6 +441,11 @@ scoped_refptr<ContextProviderCommandBuffer> CreateOffscreenContext(
       attributes, nullptr, type));
 }
 
+void SetRAILModeOnWorker(v8::RAILMode rail_mode) {
+  if (v8::Isolate* isolate = v8::Isolate::GetCurrent())

[jochen (gone - plz use gerrit), 2016/06/28 13:20:58]

the latest and greatest is introducing helper functions like
blink::MemoryPressureNotificationToWorkerThreadIsolates

[Sami, 2016/06/28 13:53:18]

I am now aligned with the latest and greatest trends.

With this change I'm now setting the RAIL mode from a thread different from the
one owning the isolate. Hannes/Ulan/Michael, is that okay?

+    isolate->SetRAILMode(rail_mode);
+}
+
 }  // namespace
 
 // For measuring memory usage after each task. Behind a command line flag.
@@ -948,6 +953,7 @@ void RenderThreadImpl::Shutdown() {
   // Shut down the message loop and the renderer scheduler before shutting down
   // Blink. This prevents a scenario where a pending task in the message loop
   // accesses Blink objects after Blink shuts down.
+  renderer_scheduler_->SetRAILModeObserver(nullptr);
   renderer_scheduler_->Shutdown();
   if (main_message_loop_)
     main_message_loop_->RunUntilIdle();
@@ -1161,6 +1167,7 @@ void RenderThreadImpl::InitializeWebKit(
   v8::Isolate* isolate = blink::mainThreadIsolate();
   isolate->SetCreateHistogramFunction(CreateHistogram);
   isolate->SetAddHistogramSampleFunction(AddHistogramSample);
+  renderer_scheduler_->SetRAILModeObserver(this);
 
   main_thread_compositor_task_runner_ =
       renderer_scheduler_->CompositorTaskRunner();
@@ -1628,6 +1635,12 @@ bool RenderThreadImpl::IsThreadedAnimationEnabled() {
   return is_threaded_animation_enabled_;
 }
 
+void RenderThreadImpl::OnRAILModeChanged(v8::RAILMode rail_mode) {
+  blink::mainThreadIsolate()->SetRAILMode(rail_mode);
+  WorkerThreadRegistry::Instance()->PostTaskToAllThreads(
+      base::Bind(&SetRAILModeOnWorker, rail_mode));
+}
+
 bool RenderThreadImpl::IsMainThread() {
   return !!current();
 }