Enforce marking "override" for functions overriding Blink in components/.

components/scheduler/child/webthread_impl_for_worker_scheduler_unittest.cc

 // Copyright 2015 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 "components/scheduler/child/webthread_impl_for_worker_scheduler.h"
 
 #include "base/synchronization/waitable_event.h"
 #include "components/scheduler/child/web_scheduler_impl.h"
 #include "components/scheduler/child/worker_scheduler_impl.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/WebKit/public/platform/WebTraceLocation.h"
 
 using testing::_;
 using testing::AnyOf;
 using testing::ElementsAre;
 using testing::Invoke;
 
 namespace scheduler {
 namespace {
 
 class NopTask : public blink::WebTaskRunner::Task {
  public:
   ~NopTask() override {}
 
-  void run() {}
+  void run() override {}
 };
 
 class MockTask : public blink::WebTaskRunner::Task {
  public:
   ~MockTask() override {}
 
   MOCK_METHOD0(run, void());
 };
 
 class MockIdleTask : public blink::WebThread::IdleTask {
@@ skipping 147 matching lines @@
   EXPECT_CALL(*delayed_task, run()).Times(0);
 
   RunOnWorkerThread(FROM_HERE, base::Bind(&shutdownOnThread, thread_.get()));
   thread_->taskRunner()->postTask(blink::WebTraceLocation(), task.release());
   thread_->taskRunner()->postDelayedTask(blink::WebTraceLocation(),
                                          task.release(), 50ll);
   thread_.reset();
 }
 
 }  // namespace scheduler