Support single-threaded impl-side painting

cc/resources/gpu_raster_worker_pool.cc

 // Copyright 2014 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/gpu_raster_worker_pool.h"
 
 #include <algorithm>
 
 #include "base/debug/trace_event.h"
 #include "cc/output/context_provider.h"
@@ skipping 165 matching lines @@
   ScheduleTasksOnOriginThread(this, &graph_);
   task_graph_runner_->ScheduleTasks(namespace_token_, &graph_);
 
   ScheduleRunTasksOnOriginThread();
 
   std::copy(new_raster_finished_tasks,
             new_raster_finished_tasks + kNumberOfTaskSets,
             raster_finished_tasks_);
 }
 
+void GpuRasterWorkerPool::WaitForTasksToFinishRunning() {
+  task_graph_runner_->WaitForTasksToFinishRunning(namespace_token_);

[reveman, 2014/10/27 19:15:49]

This doesn't really make sense. It will block on current thread for all tasks to
run on current thread. It's guaranteed to deadlock.

NOTREACHED() or NOTIMPLEMENTED() would be better but I think we should avoid
that too if possible. See my cc/resources/rasterizer.h comment.

[enne (OOO), 2014/10/27 20:23:24]

I'm happy to change this if this is not right, but this is what you directly
suggested to me to do.

+}
+
 void GpuRasterWorkerPool::CheckForCompletedTasks() {
   TRACE_EVENT0("cc", "GpuRasterWorkerPool::CheckForCompletedTasks");
 
   task_graph_runner_->CollectCompletedTasks(namespace_token_,
                                             &completed_tasks_);
   for (Task::Vector::const_iterator it = completed_tasks_.begin();
        it != completed_tasks_.end();
        ++it) {
     RasterizerTask* task = static_cast<RasterizerTask*>(it->get());
 
@@ skipping 48 matching lines @@
 
   ScopedGpuRaster gpu_raster(context_provider_);
   task_graph_runner_->RunUntilIdle();
 
   // Draw each all of the pictures that were collected.  This will also clear
   // the pictures and canvases added to |multi_picture_draw_|
   multi_picture_draw_.draw();
 }
 
 }  // namespace cc