compositor-worker: Initialize CW machinery plumbing to compositor and fire CW rAF callbacks.

components/scheduler/child/compositor_worker_scheduler.h

 // Copyright 2016 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_COMPOSITOR_WORKER_SCHEDULER_H_
 #define COMPONENTS_SCHEDULER_CHILD_COMPOSITOR_WORKER_SCHEDULER_H_
 
 #include "base/macros.h"
+#include "components/scheduler/child/single_thread_idle_task_runner.h"
 #include "components/scheduler/child/worker_scheduler.h"
 #include "components/scheduler/scheduler_export.h"
 
 namespace base {
 class Thread;
 }
 
 namespace scheduler {
 
-class SCHEDULER_EXPORT CompositorWorkerScheduler : public WorkerScheduler {
+class SCHEDULER_EXPORT CompositorWorkerScheduler
+    : public WorkerScheduler,
+      public SingleThreadIdleTaskRunner::Delegate {
  public:
   explicit CompositorWorkerScheduler(base::Thread* thread);
   ~CompositorWorkerScheduler() override;
 
   // WorkerScheduler:
   void Init() override;
 
   // ChildScheduler:
   scoped_refptr<TaskQueue> DefaultTaskRunner() override;
   scoped_refptr<scheduler::SingleThreadIdleTaskRunner> IdleTaskRunner()
       override;
   bool ShouldYieldForHighPriorityWork() override;
   bool CanExceedIdleDeadlineIfRequired() const override;
   void AddTaskObserver(base::MessageLoop::TaskObserver* task_observer) override;
   void RemoveTaskObserver(
       base::MessageLoop::TaskObserver* task_observer) override;
   void Shutdown() override;
 
+  // SingleThreadIdleTaskRunner::Delegate:
+  void OnIdleTaskPosted() override;
+  base::TimeTicks WillProcessIdleTask() override;
+  void DidProcessIdleTask() override;
+
  private:
   base::Thread* thread_;
 
   DISALLOW_COPY_AND_ASSIGN(CompositorWorkerScheduler);
 };
 
 }  // namespace scheduler
 
 #endif  // COMPONENTS_SCHEDULER_CHILD_COMPOSITOR_WORKER_SCHEDULER_H_