cc: Implement states for Task for stricter control.

cc/tiles/gpu_image_decode_controller_unittest.cc

 // Copyright 2016 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/tiles/gpu_image_decode_controller.h"
 
 #include "cc/playback/draw_image.h"
 #include "cc/raster/tile_task.h"
 #include "cc/test/test_context_provider.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 20 matching lines @@
   return matrix;
 }
 
 void ScheduleTask(TileTask* task) {
   task->WillSchedule();
   task->ScheduleOnOriginThread(nullptr);
   task->DidSchedule();
 }
 
 void RunTask(TileTask* task) {
-  task->WillRun();
+  // TODO(prashant.n): Once ScheduleOnOriginThread() and
+  // CompleteOnOriginThread() functions are removed, modify this function
+  // accordingly. (crbug.com/599863)
+  task->state().DidSchedule();
+  task->state().DidStart();
   task->RunOnWorkerThread();
-  task->DidRun();
+  task->state().DidFinish();
 }
 
 void CompleteTask(TileTask* task) {
   task->WillComplete();
   task->CompleteOnOriginThread(nullptr);
   task->DidComplete();
 }
 
 void ProcessTask(TileTask* task) {
   ScheduleTask(task);
@@ skipping 544 matching lines @@
   ProcessTask(task->dependencies()[0].get());
   ProcessTask(task.get());
 
   // The image should be in our cache after un-ref.
   controller.UnrefImage(draw_image);
   DCHECK_GT(controller.GetBytesUsedForTesting(), 0u);
 }
 
 }  // namespace
 }  // namespace cc