Add additional error handling and null checking to ImageSkiaOperations

ui/gfx/image/image_skia_rep.h

 // 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.
 
 #ifndef UI_GFX_IMAGE_IMAGE_SKIA_REP_H_
 #define UI_GFX_IMAGE_IMAGE_SKIA_REP_H_
 
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/base/layout.h"
 #include "ui/base/ui_export.h"
+#include "ui/gfx/size.h"
 
 namespace gfx {
-class Size;
 
 // An ImageSkiaRep represents a bitmap and the scale factor it is intended for.
 class UI_EXPORT ImageSkiaRep {
  public:
   // Create null bitmap.
   ImageSkiaRep();
   ~ImageSkiaRep();
 
   // Creates a bitmap with kARGB_8888_Config config with given |size| in DIP.
   // This allocates pixels in the bitmap.
   ImageSkiaRep(const gfx::Size& size, ui::ScaleFactor scale_factor);
 
   // Creates a bitmap with given scale factor.
   // Adds ref to |src|.
   ImageSkiaRep(const SkBitmap& src, ui::ScaleFactor scale_factor);
 
   // Returns true if the backing bitmap is null.
   bool is_null() const { return bitmap_.isNull(); }
 
   // Get width and height of bitmap in DIP.
   int GetWidth() const;
   int GetHeight() const;
 
   // Get width and height of bitmap in pixels.
   int pixel_width() const { return bitmap_.width(); }
   int pixel_height() const { return bitmap_.height(); }
+  Size pixel_size() const {
+    return Size(pixel_width(), pixel_height());
+  }
 
   // Retrieves the scale that the bitmap will be painted at.
   float GetScale() const;
   ui::ScaleFactor scale_factor() const { return scale_factor_; }
 
   // Returns backing bitmap.
   const SkBitmap& sk_bitmap() const { return bitmap_; }
 
  private:
   friend class ImageSkia;
   SkBitmap& mutable_sk_bitmap() { return bitmap_; }
 
   SkBitmap bitmap_;
   ui::ScaleFactor scale_factor_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_IMAGE_IMAGE_SKIA_REP_H_