Standardize usage of virtual/override/final in cc/

cc/layers/delegated_frame_resource_collection_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 "base/bind.h"
 #include "base/run_loop.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/thread.h"
 #include "cc/layers/delegated_frame_resource_collection.h"
 #include "cc/resources/returned_resource.h"
@@ skipping 28 matching lines @@
   }
 
   TransferableResourceArray CreateResourceArray() {
     TransferableResourceArray resources;
     TransferableResource resource;
     resource.id = 444;
     resources.push_back(resource);
     return resources;
   }
 
-  virtual void UnusedResourcesAreAvailable() override {
+  void UnusedResourcesAreAvailable() override {
     resources_available_ = true;
     resource_collection_->TakeUnusedResourcesForChildCompositor(
         &returned_resources_);
     if (!resources_available_closure_.is_null())
       resources_available_closure_.Run();
   }
 
   bool ReturnAndResetResourcesAvailable() {
     bool r = resources_available_;
     resources_available_ = false;
@@ skipping 97 matching lines @@
                                              return_callback,
                                              returned_resources,
                                              null_event,
                                              main_thread_task_runner.get()));
 
   thread.Stop();
 }
 
 }  // namespace
 }  // namespace cc