Add synthetic delay points for latency testing

cc/resources/image_raster_worker_pool.cc

Index: cc/resources/image_raster_worker_pool.cc
diff --git a/cc/resources/image_raster_worker_pool.cc b/cc/resources/image_raster_worker_pool.cc
index 90572ab417dedc02c00d3d082ce2ca94643e3449..ccad0a6040d2b938e40b44d73bcb5357f46fc87b 100644
--- a/cc/resources/image_raster_worker_pool.cc
+++ b/cc/resources/image_raster_worker_pool.cc
@@ -84,9 +84,19 @@ void ImageRasterWorkerPool::ScheduleTasks(RasterTask::Queue* queue) {
   unsigned priority = 0u;
   TaskGraph graph;
 
+  bool has_tasks_required_for_activation = false;
+  for (RasterTaskVector::const_iterator it = raster_tasks().begin();
+       it != raster_tasks().end(); ++it) {
+    if (IsRasterTaskRequiredForActivation(it->get())) {
+       has_tasks_required_for_activation = true;
+       break;
+    }
+  }
+
   scoped_refptr<internal::WorkerPoolTask>
       new_raster_required_for_activation_finished_task(
-          CreateRasterRequiredForActivationFinishedTask());
+          CreateRasterRequiredForActivationFinishedTask(
+              has_tasks_required_for_activation));
   internal::GraphNode* raster_required_for_activation_finished_node =
       CreateGraphNodeForTask(
           new_raster_required_for_activation_finished_task.get(),