Standardize usage of virtual/override/final specifiers in sync/.

sync/internal_api/public/base/cancelation_signal_unittest.cc

 // Copyright 2013 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 "sync/internal_api/public/base/cancelation_signal.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/platform_thread.h"
@@ skipping 75 matching lines @@
   event_.Signal();
 }
 
 bool BlockingTask::WasStarted() {
   return was_started_;
 }
 
 class CancelationSignalTest : public ::testing::Test {
  public:
   CancelationSignalTest();
-  virtual ~CancelationSignalTest();
+  ~CancelationSignalTest() override;
 
   // Starts the blocking task on a background thread.  Does not wait for the
   // task to start.
   void StartBlockingTaskAsync();
 
   // Starts the blocking task on a background thread.  Does not return until
   // the task has been started.
   void StartBlockingTaskAndWaitForItToStart();
 
   // Cancels the blocking task.
@@ skipping 70 matching lines @@
 // progress.
 TEST_F(CancelationSignalTest, Cancel) {
   StartBlockingTaskAndWaitForItToStart();
 
   // Wait for the task to finish and let verify it has been started.
   CancelBlocking();
   EXPECT_FALSE(VerifyTaskNotStarted());
 }
 
 }  // namespace syncer