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..d24d00aa023c9a76841ab9ae7ca41b203c3376a0 100644
--- a/content/child/blink_platform_impl.cc
+++ b/content/child/blink_platform_impl.cc
@@ -418,12 +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) {
+  InternalInit();
+}
+
+BlinkPlatformImpl::BlinkPlatformImpl(
+    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) {
+  // TODO(alexclarke): Use c++11 delegated constructors when allowed.
+  InternalInit();
+}
+
+void BlinkPlatformImpl::InternalInit() {
   // ChildThread may not exist in some tests.
   if (ChildThread::current()) {
     geofencing_provider_.reset(new WebGeofencingProviderImpl(
@@ -432,6 +448,8 @@ BlinkPlatformImpl::BlinkPlatformImpl()
     notification_dispatcher_ =
         ChildThread::current()->notification_dispatcher();
   }
+
+  shared_timer_.SetTaskRunner(main_thread_task_runner_);

[Sami, 2014/11/07 05:26:25]

Do we need to check that the runner is non-null here? IIRC you mentioned in can
be null in some cases.

[alex clarke (OOO till 29th), 2014/11/07 15:19:16]

It probably doesn't hurt to check, however the problem I was getting before
where the browser tab would crash super early doesn't occur anymore.  I'll add
it if you like.

[Sami, 2014/11/07 18:48:33]

Ok, I'm still a bit confused how this thing would be null in practice. However
to be consistent we shouldn't then need the null check in currentThread either,
right?

[alex clarke (OOO till 29th), 2014/11/07 19:18:56]

As discussed offline I added the null check here too since the other one is
needed.

 }
 
 BlinkPlatformImpl::~BlinkPlatformImpl() {
@@ -490,12 +508,18 @@ blink::WebThread* BlinkPlatformImpl::currentThread() {
   if (thread)
     return (thread);
 
-  scoped_refptr<base::MessageLoopProxy> message_loop =
-      base::MessageLoopProxy::current();
-  if (!message_loop.get())
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner;
+  if (main_thread_task_runner_.get() &&
+      main_thread_task_runner_->BelongsToCurrentThread()) {
+    task_runner = main_thread_task_runner_;
+  } else {
+    task_runner = base::MessageLoopProxy::current();
+  }
+
+  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 +1016,7 @@ 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(