Update {virtual,override,final} to follow C++11 style.

chrome/browser/android/thumbnail/thumbnail.h

 // Copyright 2014 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.
 
 #ifndef CHROME_BROWSER_ANDROID_THUMBNAIL_THUMBNAIL_H_
 #define CHROME_BROWSER_ANDROID_THUMBNAIL_THUMBNAIL_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/time/time.h"
 #include "cc/resources/ui_resource_bitmap.h"
@@ skipping 24 matching lines @@
 };
 
 class Thumbnail : public ui::UIResourceClientAndroid {
  public:
   static scoped_ptr<Thumbnail> Create(
       TabId tab_id,
       const base::Time& time_stamp,
       float scale,
       ui::UIResourceProvider* ui_resource_provider,
       ThumbnailDelegate* thumbnail_delegate);
-  virtual ~Thumbnail();
+  ~Thumbnail() override;
 
   TabId tab_id() const { return tab_id_; }
   base::Time time_stamp() const { return time_stamp_; }
   float scale() const { return scale_; }
   cc::UIResourceId ui_resource_id() const { return ui_resource_id_; }
   const gfx::SizeF& scaled_content_size() const { return scaled_content_size_; }
   const gfx::SizeF& scaled_data_size() const { return scaled_data_size_; }
 
   void SetBitmap(const SkBitmap& bitmap);
   void SetCompressedBitmap(skia::RefPtr<SkPixelRef> compressed_bitmap,
                            const gfx::Size& content_size);
   void CreateUIResource();
 
   // content::UIResourceClient implementation.
-  virtual cc::UIResourceBitmap GetBitmap(cc::UIResourceId uid,
-                                         bool resource_lost) override;
+  cc::UIResourceBitmap GetBitmap(cc::UIResourceId uid,
+                                 bool resource_lost) override;
 
   // ui::UIResourceClientAndroid implementation.
-  virtual void UIResourceIsInvalid() override;
+  void UIResourceIsInvalid() override;
 
  protected:
   Thumbnail(TabId tab_id,
             const base::Time& time_stamp,
             float scale,
             ui::UIResourceProvider* ui_resource_provider,
             ThumbnailDelegate* thumbnail_delegate);
 
   void ClearUIResourceId();
 
   TabId tab_id_;
   base::Time time_stamp_;
   float scale_;
 
   gfx::SizeF scaled_content_size_;
   gfx::SizeF scaled_data_size_;
 
   cc::UIResourceBitmap bitmap_;
   cc::UIResourceId ui_resource_id_;
 
   bool retrieved_;
 
   ui::UIResourceProvider* ui_resource_provider_;
   ThumbnailDelegate* thumbnail_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(Thumbnail);
 };
 
 #endif  // CHROME_BROWSER_ANDROID_THUMBNAIL_THUMBNAIL_H_