Support single-threaded impl-side painting

cc/resources/zero_copy_raster_worker_pool.cc

 // Copyright 2013 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/resources/zero_copy_raster_worker_pool.h"
 
 #include <algorithm>
 
 #include "base/debug/trace_event.h"
 #include "base/debug/trace_event_argument.h"
@@ skipping 158 matching lines @@
 
     task->WillComplete();
     task->CompleteOnOriginThread(this);
     task->DidComplete();
 
     task->RunReplyOnOriginThread();
   }
   completed_tasks_.clear();
 }
 
+void ZeroCopyRasterWorkerPool::WaitForTasksToFinishRunning() {
+  task_graph_runner_->WaitForTasksToFinishRunning(namespace_token_);
+}
+
 scoped_ptr<RasterBuffer> ZeroCopyRasterWorkerPool::AcquireBufferForRaster(
     const Resource* resource) {
   return make_scoped_ptr<RasterBuffer>(
       new RasterBufferImpl(resource_provider_, resource));
 }
 
 void ZeroCopyRasterWorkerPool::ReleaseBufferForRaster(
     scoped_ptr<RasterBuffer> buffer) {
   // Nothing to do here. RasterBufferImpl destructor cleans up after itself.
 }
@@ skipping 19 matching lines @@
       new base::debug::TracedValue();
 
   state->BeginArray("tasks_pending");
   for (TaskSet task_set = 0; task_set < kNumberOfTaskSets; ++task_set)
     state->AppendBoolean(raster_pending_[task_set]);
   state->EndArray();
   return state;
 }
 
 }  // namespace cc