[Reland] Make canceling Timers fast.

third_party/WebKit/Source/platform/scheduler/base/task_queue_manager.cc

Index: third_party/WebKit/Source/platform/scheduler/base/task_queue_manager.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/base/task_queue_manager.cc b/third_party/WebKit/Source/platform/scheduler/base/task_queue_manager.cc
index f44ee457a87e5189ddb438b495d6db1920f95be9..9d1b182dba0decec44806a75e22ec354ea243e6c 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/task_queue_manager.cc
+++ b/third_party/WebKit/Source/platform/scheduler/base/task_queue_manager.cc
@@ -282,12 +282,18 @@ TaskQueueManager::ProcessTaskResult TaskQueueManager::ProcessTaskFromWorkQueue(
 
   internal::TaskQueueImpl::Task pending_task =
       work_queue->TakeTaskFromWorkQueue();
+
+  // It's possible the task was canceled, if so bail out.
+  if (pending_task.task.IsCancelled())
+    return ProcessTaskResult::EXECUTED;
+
   if (!pending_task.nestable && delegate_->IsNested()) {
     // Defer non-nestable work to the main task runner.  NOTE these tasks can be
     // arbitrarily delayed so the additional delay should not be a problem.
     // TODO(skyostil): Figure out a way to not forget which task queue the
     // task is associated with. See http://crbug.com/522843.
-    delegate_->PostNonNestableTask(pending_task.posted_from, pending_task.task);
+    delegate_->PostNonNestableTask(pending_task.posted_from,
+                                   std::move(pending_task.task));
     return ProcessTaskResult::DEFERRED;
   }