Add skia::RefPtr class to wrap ref counted classes from Skia.

ui/gfx/skia_util.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_SKIA_UTIL_H_
 #define UI_GFX_SKIA_UTIL_H_
 
 #include <string>
 #include <vector>
 
+#include "skia/ext/refptr.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "third_party/skia/include/core/SkRect.h"
 #include "third_party/skia/include/core/SkShader.h"
 #include "ui/base/ui_export.h"
 
 class SkBitmap;
 class SkDrawLooper;
 
 namespace gfx {
 
 class ImageSkiaRep;
 class Rect;
 class RectF;
 class ShadowValue;
 
 // Convert between Skia and gfx rect types.
 UI_EXPORT SkRect RectToSkRect(const Rect& rect);
 UI_EXPORT SkIRect RectToSkIRect(const Rect& rect);
 UI_EXPORT Rect SkIRectToRect(const SkIRect& rect);
 UI_EXPORT SkRect RectFToSkRect(const RectF& rect);
 UI_EXPORT RectF SkRectToRectF(const SkRect& rect);
 
 // Creates a bitmap shader for the image rep with the image rep's scale factor.
 // Sets the created shader's local matrix such that it displays the image rep at
 // the correct scale factor.
 // The shader's local matrix should not be changed after the shader is created.
 // TODO(pkotwicz): Allow shader's local matrix to be changed after the shader
 // is created.
-// Example usage to avoid leaks:
-//   SkSafeUnref(paint.setShader(gfx::CreateImageRepShader(image_rep,
-//       tile_mode, matrix)));
 //
-// (The old shader in the paint, if any, needs to be freed, and SkSafeUnref will
-// handle the NULL case.)
-UI_EXPORT SkShader* CreateImageRepShader(const gfx::ImageSkiaRep& image_rep,
-                                         SkShader::TileMode tile_mode,
-                                         const SkMatrix& local_matrix);
+UI_EXPORT skia::RefPtr<SkShader> CreateImageRepShader(
+    const gfx::ImageSkiaRep& image_rep,
+    SkShader::TileMode tile_mode,
+    const SkMatrix& local_matrix);
 
 // Creates a vertical gradient shader. The caller owns the shader.
 // Example usage to avoid leaks:
-//   SkSafeUnref(paint.setShader(gfx::CreateGradientShader(0, 10, red, blue)));
-//
-// (The old shader in the paint, if any, needs to be freed, and SkSafeUnref will
-// handle the NULL case.)
-UI_EXPORT SkShader* CreateGradientShader(int start_point,
-                                         int end_point,
-                                         SkColor start_color,
-                                         SkColor end_color);
+UI_EXPORT skia::RefPtr<SkShader> CreateGradientShader(int start_point,
+                                                      int end_point,
+                                                      SkColor start_color,
+                                                      SkColor end_color);
 
 // Creates a draw looper to generate |shadows|. The caller owns the draw looper.
 // NULL is returned if |shadows| is empty since no draw looper is needed in
 // this case.
-// Example usage to avoid leaks:
-//   SkSafeUnref(paint.setDrawLooper(gfx::CreateShadowDrawLooper(shadows)));
-UI_EXPORT SkDrawLooper* CreateShadowDrawLooper(
+UI_EXPORT skia::RefPtr<SkDrawLooper> CreateShadowDrawLooper(
     const std::vector<ShadowValue>& shadows);
 
 // Returns true if the two bitmaps contain the same pixels.
 UI_EXPORT bool BitmapsAreEqual(const SkBitmap& bitmap1,
                                const SkBitmap& bitmap2);
 
 // Converts Skia ARGB format pixels in |skia| to RGBA.
 UI_EXPORT void ConvertSkiaToRGBA(const unsigned char* skia,
                                  int pixel_width,
                                  unsigned char* rgba);
 
 }  // namespace gfx
 
 #endif  // UI_GFX_SKIA_UTIL_H_