compositor worker: Use a WebThread for the compositor thread.

components/scheduler/child/webthread_impl_for_worker_scheduler.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_SCHEDULER_CHILD_WEBTHREAD_IMPL_FOR_WORKER_SCHEDULER_H_
 #define COMPONENTS_SCHEDULER_CHILD_WEBTHREAD_IMPL_FOR_WORKER_SCHEDULER_H_
 
 #include "base/threading/thread.h"
 #include "components/scheduler/base/task_queue_manager.h"
 #include "components/scheduler/child/webthread_base.h"
@@ skipping 29 matching lines @@
   blink::PlatformThreadId threadId() const override;
   blink::WebTaskRunner* taskRunner() override;
 
   // WebThreadBase implementation.
   base::SingleThreadTaskRunner* TaskRunner() const override;
   scheduler::SingleThreadIdleTaskRunner* IdleTaskRunner() const override;
 
   // base::MessageLoop::DestructionObserver implementation.
   void WillDestroyCurrentMessageLoop() override;
 
+ protected:
+  base::Thread* thread() const { return thread_.get(); }
+
  private:
-  // Returns whether the base::Thread's task-runner should be used as the
-  // default task runner (returns true), or the default task runner from the
-  // scheduler should be used instead (returns false). The default behaviour is
-  // to use the scheduler's default task runner.
-  virtual bool UseThreadTaskRunnerAsDefault() const;
+  virtual scoped_ptr<scheduler::WorkerScheduler> CreateWorkerScheduler();

[Sami, 2016/01/14 13:55:04]

Looks like this patch is relative to your older one instead of tip-of-tree.
Could you rebase?

[sadrul, 2016/01/14 15:20:40]

Yep, sorry. Done.

 
   void AddTaskObserverInternal(
       base::MessageLoop::TaskObserver* observer) override;
   void RemoveTaskObserverInternal(
       base::MessageLoop::TaskObserver* observer) override;
 
   void InitOnThread(base::WaitableEvent* completion);
   void RestoreTaskRunnerOnThread(base::WaitableEvent* completion);
 
   scoped_ptr<base::Thread> thread_;
   scoped_ptr<scheduler::WorkerScheduler> worker_scheduler_;
   scoped_ptr<scheduler::WebSchedulerImpl> web_scheduler_;
   scoped_refptr<base::SingleThreadTaskRunner> thread_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   scoped_refptr<scheduler::SingleThreadIdleTaskRunner> idle_task_runner_;
   scoped_refptr<SchedulerTqmDelegate> task_runner_delegate_;
   scoped_ptr<WebTaskRunnerImpl> web_task_runner_;
 };
 
 }  // namespace scheduler
 
 #endif  // COMPONENTS_SCHEDULER_CHILD_WEBTHREAD_IMPL_FOR_WORKER_SCHEDULER_H_