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

components/scheduler/child/compositor_worker_scheduler.cc

 // 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.
 
 #include "components/scheduler/child/compositor_worker_scheduler.h"
 
 #include "base/message_loop/message_loop.h"
 #include "base/threading/thread.h"
 
 namespace scheduler {
@@ skipping 105 matching lines @@
 
 scoped_refptr<TaskQueue> CompositorWorkerScheduler::DefaultTaskRunner() {
   // TODO(sad): Implement a more robust scheduler that can do idle tasks for GC
   // without regressing performance of the rest of the system.
   return make_scoped_refptr(
       new CompositorWorkerTaskRunnerWrapper(thread_->task_runner()));
 }
 
 scoped_refptr<scheduler::SingleThreadIdleTaskRunner>
 CompositorWorkerScheduler::IdleTaskRunner() {
-  // TODO(sad): Not having a task-runner for idle tasks means v8 has to fallback
-  // to inline GC, which might cause jank.
-  return nullptr;
+  // TODO(flackr): This posts idle tasks as regular tasks. We need to create
+  // an idle task runner with the semantics we want for the compositor thread
+  // which runs them after the current frame has been drawn before the next
+  // vsync. https://crbug.com/609532
+  return make_scoped_refptr(new SingleThreadIdleTaskRunner(
+      thread_->task_runner(), thread_->task_runner(), this,
+      "compositor.scheduler"));
 }
 
 bool CompositorWorkerScheduler::CanExceedIdleDeadlineIfRequired() const {
   return false;
 }
 
 bool CompositorWorkerScheduler::ShouldYieldForHighPriorityWork() {
   return false;
 }
 
 void CompositorWorkerScheduler::AddTaskObserver(
     base::MessageLoop::TaskObserver* task_observer) {
   thread_->message_loop()->AddTaskObserver(task_observer);
 }
 
 void CompositorWorkerScheduler::RemoveTaskObserver(
     base::MessageLoop::TaskObserver* task_observer) {
   thread_->message_loop()->RemoveTaskObserver(task_observer);
 }
 
 void CompositorWorkerScheduler::Shutdown() {}
 
+void CompositorWorkerScheduler::OnIdleTaskPosted() {}
+
+base::TimeTicks CompositorWorkerScheduler::WillProcessIdleTask() {
+  // TODO(flackr): Return the next frame time as the deadline instead.
+  // TODO(flackr): Ensure that oilpan GC does happen on the compositor thread
+  // even though we will have no long idle periods. https://crbug.com/609531
+  return base::TimeTicks::Now() + base::TimeDelta::FromMillisecondsD(16.7);
+}
+
+void CompositorWorkerScheduler::DidProcessIdleTask() {}
+
 }  // namespace scheduler