Implement remaining SkBitmapOperations as ImageSkiaOperations

ui/gfx/image/image_skia_operations.h

Index: ui/gfx/image/image_skia_operations.h
diff --git a/ui/gfx/image/image_skia_operations.h b/ui/gfx/image/image_skia_operations.h
index e725602f2b084cc0bae656afd9c5cc18c23162b4..605bd0ebef6b07c73b43f942d15fe73012d772e1 100644
--- a/ui/gfx/image/image_skia_operations.h
+++ b/ui/gfx/image/image_skia_operations.h
@@ -7,10 +7,12 @@
 
 #include "base/gtest_prod_util.h"
 #include "ui/base/ui_export.h"
-#include "ui/gfx/size.h"
+#include "ui/gfx/color_utils.h"
 
 namespace gfx {
 class ImageSkia;
+class Rect;
+class Size;
 
 class UI_EXPORT ImageSkiaOperations {
  public:
@@ -34,6 +36,20 @@ class UI_EXPORT ImageSkiaOperations {
                                     int src_x, int src_y,
                                     int dst_w, int dst_h);
 
+  // We create a button background image by compositing the color and image

[sky, 2012/07/16 21:23:40]

We create -> Creates

+  // together, then applying the mask. This is a highly specialized composite
+  // operation that is the equivalent of drawing a background in |color|,
+  // tiling |image| over the top, and then masking the result out with |mask|.
+  // The images must use kARGB_8888_Config config.
+  static ImageSkia CreateButtonBackground(SkColor color,
+                                          const gfx::ImageSkia& image,
+                                          const gfx::ImageSkia& mask);
+
+  // Returns an image which is a subset of |image| with bounds |subset_bounds|.
+  // |image| cannot have image reps of |kA1_Config| config.

[sky, 2012/07/16 21:23:40]

What does this second line mean?
kAll_Config?

[pkotwicz, 2012/07/17 01:15:41]

The config of the bitmaps contained by the ImageSkia on which ExtractSubset
operates on cannot be kA1_Config. 
kA1_Config is a config simillar to kARGB_8888_Config. SkBitmap::extractSubset is
not supported for kA1_Config.

[sky, 2012/07/20 23:21:25]

Make the comment clearer than. Right now it is confusing.

+  static ImageSkia ExtractSubset(const gfx::ImageSkia& image,
+                                 const gfx::Rect& subset_bounds);
+
   // Creates an image that resizes |source| to given |target_size_in_dip|.
   // The resize operation occurs synchronously at the time that the desired
   // scale factor is known (either GetRepresentation is called or the image