cc: Implement states for Task for stricter control.

cc/raster/single_thread_task_graph_runner.cc

Index: cc/raster/single_thread_task_graph_runner.cc
diff --git a/cc/raster/single_thread_task_graph_runner.cc b/cc/raster/single_thread_task_graph_runner.cc
index ba879af6cb12d00150cb7346bd1f9ef8950d5645..56ae382e7203ff1ec175c9def3d13c31151a88df 100644
--- a/cc/raster/single_thread_task_graph_runner.cc
+++ b/cc/raster/single_thread_task_graph_runner.cc
@@ -148,17 +148,11 @@ bool SingleThreadTaskGraphRunner::RunTaskWithLockAcquired() {
   auto prioritized_task = work_queue_.GetNextTaskToRun(category);
   Task* task = prioritized_task.task;
 
-  // Call WillRun() before releasing |lock_| and running task.
-  task->WillRun();
-
   {
     base::AutoUnlock unlock(lock_);
     task->RunOnWorkerThread();
   }
 
-  // This will mark task as finished running.
-  task->DidRun();
-
   work_queue_.CompleteTask(prioritized_task);
 
   // If namespace has finished running all tasks, wake up origin thread.