WebThreadImplForMessageLoop to use blink scheduler

content/child/blink_platform_impl.cc

Index: content/child/blink_platform_impl.cc
diff --git a/content/child/blink_platform_impl.cc b/content/child/blink_platform_impl.cc
index 79f72adcffcbe5daa58d9d36e8d9587f52cc11ce..812a074fe19aa05513aad5f84b9ac59280144ae3 100644
--- a/content/child/blink_platform_impl.cc
+++ b/content/child/blink_platform_impl.cc
@@ -418,13 +418,28 @@ static int ToMessageID(WebLocalizedString::Name name) {
 }
 
 BlinkPlatformImpl::BlinkPlatformImpl()
-    : main_loop_(base::MessageLoop::current()),
+    : main_thread_task_runner_(base::MessageLoopProxy::current()),
       shared_timer_func_(NULL),
       shared_timer_fire_time_(0.0),
       shared_timer_fire_time_was_set_while_suspended_(false),
       shared_timer_suspended_(0),
       current_thread_slot_(&DestroyCurrentThread) {
-  // ChildThread may not exist in some tests.
+  InternalInit();
+}
+
+BlinkPlatformImpl::BlinkPlatformImpl(

[Sami, 2014/11/06 00:22:59]

Delegated constructors still blocked it looks like:
https://codereview.chromium.org/695683002/

If we're sufficiently bothered about this we could consider helping to get them
accepted.

[alex clarke (OOO till 29th), 2014/11/06 00:40:49]

Lets just get this patch in :)  I can add a fixme to use them when available.

+    scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner)
+    : main_thread_task_runner_(main_thread_task_runner),
+      shared_timer_func_(NULL),
+      shared_timer_fire_time_(0.0),
+      shared_timer_fire_time_was_set_while_suspended_(false),
+      shared_timer_suspended_(0),
+      current_thread_slot_(&DestroyCurrentThread) {
+  InternalInit();
+}
+
+void BlinkPlatformImpl::InternalInit() {
+    // ChildThread may not exist in some tests.
   if (ChildThread::current()) {
     geofencing_provider_.reset(new WebGeofencingProviderImpl(
         ChildThread::current()->thread_safe_sender()));
@@ -490,12 +505,17 @@ blink::WebThread* BlinkPlatformImpl::currentThread() {
   if (thread)
     return (thread);
 
-  scoped_refptr<base::MessageLoopProxy> message_loop =
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner =
       base::MessageLoopProxy::current();
-  if (!message_loop.get())
+  if (main_thread_task_runner_.get() &&
+      main_thread_task_runner_->BelongsToCurrentThread()) {

[Sami, 2014/11/06 00:22:59]

Could you rewrite this in a way that we don't do the TLS lookup
MessageLoopProxy::current() if we've got a valid main_thread_task_runner?

[alex clarke (OOO till 29th), 2014/11/06 00:40:49]

Done.

+    task_runner = main_thread_task_runner_;
+  }
+
+  if (!task_runner.get())
     return NULL;
 
-  thread = new WebThreadImplForMessageLoop(message_loop.get());
+  thread = new WebThreadImplForMessageLoop(task_runner);
   current_thread_slot_.Set(thread);
   return thread;
 }
@@ -992,7 +1012,7 @@ void BlinkPlatformImpl::stopSharedTimer() {
 
 void BlinkPlatformImpl::callOnMainThread(
     void (*func)(void*), void* context) {
-  main_loop_->PostTask(FROM_HERE, base::Bind(func, context));
+  main_thread_task_runner_->PostTask(FROM_HERE, base::Bind(func, context));
 }
 
 blink::WebGestureCurve* BlinkPlatformImpl::createFlingAnimationCurve(