mac: Remove implicit conversion from ImageSkia to SkBitmap.

ui/gfx/image/image_skia.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_H_
 #define UI_GFX_IMAGE_IMAGE_SKIA_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 42 matching lines @@
   // Copies a reference to |other|'s storage.
   ImageSkia& operator=(const ImageSkia& other);
 
   // Converts from SkBitmap.
   // Adds ref to passed in bitmap.
   // DIP width and height are set based on scale factor of 1x.
   // TODO(pkotwicz): This is temporary till conversion to gfx::ImageSkia is
   // done.
   ImageSkia& operator=(const SkBitmap& other);
 
-#if defined(OS_MACOSX) || defined(OS_WIN)
+#if defined(OS_WIN)
   // Converts to gfx::ImageSkiaRep and SkBitmap.
   // TODO(pkotwicz): This is temporary till conversion to gfx::ImageSkia is
   // done.
   operator SkBitmap&() const { return GetBitmap(); }
 #endif
 
   ~ImageSkia();
 
   // Returns true if this object is backed by the same ImageSkiaStorage as
   // |other|. Will also return true if both images are isNull().
@@ skipping 61 matching lines @@
 
   SkBitmap& GetBitmap() const;
 
   // A refptr so that ImageRepSkia can be copied cheaply.
   scoped_refptr<internal::ImageSkiaStorage> storage_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_IMAGE_IMAGE_SKIA_H_