Warn on missing OVERRIDE/virtual everywhere, not just in header files.

ui/gfx/image/image.cc

 // Copyright (c) 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.
 
 #include "ui/gfx/image/image.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 324 matching lines @@
     CHECK(pixbuf);
   }
 
   virtual ~ImageRepGdk() {
     if (pixbuf_) {
       g_object_unref(pixbuf_);
       pixbuf_ = NULL;
     }
   }
 
-  virtual int Width() const {
+  virtual int Width() const OVERRIDE {
     return gdk_pixbuf_get_width(pixbuf_);
   }
 
-  virtual int Height() const {
+  virtual int Height() const OVERRIDE {
     return gdk_pixbuf_get_height(pixbuf_);
   }
 
-  virtual gfx::Size Size() const {
+  virtual gfx::Size Size() const OVERRIDE {
     return gfx::Size(Width(), Height());
   }
 
   GdkPixbuf* pixbuf() const { return pixbuf_; }
 
  private:
   GdkPixbuf* pixbuf_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageRepGdk);
 };
 
 // Represents data that lives on the display server instead of in the client.
 class ImageRepCairo : public ImageRep {
  public:
   explicit ImageRepCairo(GdkPixbuf* pixbuf)
       : ImageRep(Image::kImageRepCairo),
         cairo_cache_(new CairoCachedSurface) {
     CHECK(pixbuf);
     cairo_cache_->UsePixbuf(pixbuf);
   }
 
   virtual ~ImageRepCairo() {
     delete cairo_cache_;
   }
 
-  virtual int Width() const {
+  virtual int Width() const OVERRIDE {
     return cairo_cache_->Width();
   }
 
-  virtual int Height() const {
+  virtual int Height() const OVERRIDE {
     return cairo_cache_->Height();
   }
 
-  virtual gfx::Size Size() const {
+  virtual gfx::Size Size() const OVERRIDE {
     return gfx::Size(Width(), Height());
   }
 
   CairoCachedSurface* surface() const { return cairo_cache_; }
 
  private:
   CairoCachedSurface* cairo_cache_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageRepCairo);
 };
@@ skipping 517 matching lines @@
   }
   return it->second;
 }
 
 void Image::AddRepresentation(internal::ImageRep* rep) const {
   CHECK(storage_.get());
   storage_->representations().insert(std::make_pair(rep->type(), rep));
 }
 
 }  // namespace gfx