Support single-threaded impl-side painting

cc/test/fake_tile_manager.cc

 // Copyright 2012 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/test/fake_tile_manager.h"
 
 #include <deque>
 
 #include "base/lazy_instance.h"
 #include "cc/resources/raster_buffer.h"
@@ skipping 15 matching lines @@
          ++it) {
       RasterTask* task = it->task;
 
       task->WillSchedule();
       task->ScheduleOnOriginThread(this);
       task->DidSchedule();
 
       completed_tasks_.push_back(task);
     }
   }
+  void WaitForTasksToFinishRunning() override {
+    // Everything completes instantly; nothing to do.
+  }
   void CheckForCompletedTasks() override {
     for (RasterTask::Vector::iterator it = completed_tasks_.begin();
          it != completed_tasks_.end();
          ++it) {
       RasterTask* task = it->get();
 
       task->WillComplete();
       task->CompleteOnOriginThread(this);
       task->DidComplete();
 
@@ skipping 49 matching lines @@
 }
 
 void FakeTileManager::Release(Tile* tile) {
   TileManager::Release(tile);
 
   FreeResourcesForReleasedTiles();
   CleanUpReleasedTiles();
 }
 
 }  // namespace cc