content: Implement dynamic priorities for raster threads.

cc/raster/synchronous_task_graph_runner.cc

 // 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.
 
 #include "cc/raster/synchronous_task_graph_runner.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <utility>
 
 #include "base/threading/simple_thread.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/trace_event/trace_event.h"
 
 namespace cc {
 
-SynchronousTaskGraphRunner::SynchronousTaskGraphRunner() {}
+SynchronousTaskGraphRunner::SynchronousTaskGraphRunner() : work_queue_(this) {}
 
 SynchronousTaskGraphRunner::~SynchronousTaskGraphRunner() {
   DCHECK(!work_queue_.HasReadyToRunTasks());
 }
 
 NamespaceToken SynchronousTaskGraphRunner::GetNamespaceToken() {
   return work_queue_.GetNamespaceToken();
 }
 
 void SynchronousTaskGraphRunner::ScheduleTasks(NamespaceToken token,
@@ skipping 59 matching lines @@
   task->WillRun();
   task->RunOnWorkerThread();
   task->DidRun();
 
   work_queue_.CompleteTask(prioritized_task);
 
   return true;
 }
 
 }  // namespace cc