Standardize usage of virtual/override/final in cc/

cc/resources/picture_pile_impl.h

 // Copyright 2012 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 CC_RESOURCES_PICTURE_PILE_IMPL_H_
 #define CC_RESOURCES_PICTURE_PILE_IMPL_H_
 
 #include <list>
 #include <map>
 #include <set>
@@ skipping 88 matching lines @@
   };
 
   void DidBeginTracing();
 
  protected:
   friend class PicturePile;
   friend class PixelRefIterator;
 
   PicturePileImpl();
   explicit PicturePileImpl(const PicturePileBase* other);
-  virtual ~PicturePileImpl();
+  ~PicturePileImpl() override;
 
  private:
   typedef std::map<const Picture*, Region> PictureRegionMap;
 
   void CoalesceRasters(const gfx::Rect& canvas_rect,
                        const gfx::Rect& content_rect,
                        float contents_scale,
                        PictureRegionMap* result) const;
 
   void RasterCommon(
       SkCanvas* canvas,
       SkDrawPictureCallback* callback,
       const gfx::Rect& canvas_rect,
       float contents_scale,
       RenderingStatsInstrumentation* rendering_stats_instrumentation,
       bool is_analysis) const;
 
   DISALLOW_COPY_AND_ASSIGN(PicturePileImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PICTURE_PILE_IMPL_H_