Add synthetic delay points for latency testing

cc/resources/image_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/image_raster_worker_pool.h"
 
 #include "base/debug/trace_event.h"
 #include "base/values.h"
 #include "cc/debug/traced_value.h"
 #include "cc/resources/resource.h"
@@ skipping 68 matching lines @@
     TRACE_EVENT_ASYNC_BEGIN0("cc", "ScheduledTasks", this);
 
   raster_tasks_pending_ = true;
   raster_tasks_required_for_activation_pending_ = true;
 
   unsigned priority = 0u;
   TaskGraph graph;
 
   scoped_refptr<internal::WorkerPoolTask>
       new_raster_required_for_activation_finished_task(
-          CreateRasterRequiredForActivationFinishedTask());
+          CreateRasterRequiredForActivationFinishedTask(
+              raster_tasks_required_for_activation().size()));
   internal::GraphNode* raster_required_for_activation_finished_node =
       CreateGraphNodeForTask(
           new_raster_required_for_activation_finished_task.get(),
           priority++,
           &graph);
 
   scoped_refptr<internal::WorkerPoolTask> new_raster_finished_task(
       CreateRasterFinishedTask());
   internal::GraphNode* raster_finished_node =
       CreateGraphNodeForTask(new_raster_finished_task.get(),
@@ skipping 126 matching lines @@
   if (is_required_for_activation) {
     raster_required_for_activation_finished_node->add_dependency();
     image_node->add_dependent(raster_required_for_activation_finished_node);
   }
 
   raster_finished_node->add_dependency();
   image_node->add_dependent(raster_finished_node);
 }
 
 }  // namespace cc