Adds a gfx_export.h to ui/gfx and converts all code in ui/gfx to

ui/gfx/image/canvas_image_source.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_CANVAS_IMAGE_SOURCE_H_
 #define UI_GFX_IMAGE_CANVAS_IMAGE_SOURCE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
-#include "ui/base/ui_export.h"
+#include "ui/gfx/gfx_export.h"
 #include "ui/gfx/image/image_skia_source.h"
 #include "ui/gfx/size.h"
 
 namespace gfx {
 class Canvas;
 class ImageSkiaRep;
 
 // CanvasImageSource is useful if you need to generate an image for
 // a scale factor using gfx::Canvas. It creates a new Canvas
 // with target scale factor and generates ImageSkiaRep when drawing is
@@ skipping 16 matching lines @@
   virtual ~CanvasImageSource() {}
 
   const gfx::Size size_;
   const bool is_opaque_;
   DISALLOW_COPY_AND_ASSIGN(CanvasImageSource);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_IMAGE_CANVAS_IMAGE_SOURCE_H_