Standardize usage of virtual/override/final in gin/

gin/modules/timer_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 "gin/modules/timer.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "gin/handle.h"
 #include "gin/object_template_builder.h"
@@ skipping 19 matching lines @@
   void set_count(int count) { count_ = count; }
 
   void Quit() {
     base::MessageLoop::current()->QuitNow();
   }
 
  private:
   Result() : count_(0) {
   }
 
-  virtual ~Result() {
-  }
+  ~Result() override {}
 
-  virtual ObjectTemplateBuilder GetObjectTemplateBuilder(
+  ObjectTemplateBuilder GetObjectTemplateBuilder(
       v8::Isolate* isolate) override {
     return Wrappable<Result>::GetObjectTemplateBuilder(isolate)
         .SetProperty("count", &Result::count, &Result::set_count)
         .SetMethod("quit", &Result::Quit);
   }
 
   int count_;
 };
 
 WrapperInfo Result::kWrapperInfo = { gin::kEmbedderNativeGin };
@@ skipping 92 matching lines @@
   // Destroy runner, which should destroy the timer object we created.
   helper.QuitSoon();
   helper.runner.reset(NULL);
   helper.loop.Run();
 
   // Timer should not have run because it was deleted.
   EXPECT_EQ(0, helper.result->count());
 }
 
 }  // namespace gin