Add support for PNG representation in gfx::Image

ui/gfx/image/image.h

Index: ui/gfx/image/image.h
diff --git a/ui/gfx/image/image.h b/ui/gfx/image/image.h
index c03db3ad18e783231e57e53712350e10e925f0c6..f6d021fa62ea93ba4dacae1e8f0a1540e3a34db5 100644
--- a/ui/gfx/image/image.h
+++ b/ui/gfx/image/image.h
@@ -36,6 +36,7 @@ class ImageMacTest;
 }
 
 namespace gfx {
+class ImagePNG;
 class ImageSkia;
 class ImageSkiaRep;
 
@@ -55,6 +56,7 @@ class UI_EXPORT Image {
     kImageRepCocoa,
     kImageRepCairo,
     kImageRepSkia,
+    kImageRepPNG,
   };
 
   typedef std::map<RepresentationType, internal::ImageRep*> RepresentationMap;
@@ -62,6 +64,10 @@ class UI_EXPORT Image {
   // Creates an empty image with no representations.
   Image();
 
+  // Creates a new image by copying the ImagePNG for use as the default
+  // representation.
+  explicit Image(const ImagePNG& png);
+
   // Creates a new image by copying the ImageSkia for use as the default
   // representation.
   explicit Image(const ImageSkia& image);
@@ -98,6 +104,7 @@ class UI_EXPORT Image {
   // Converts the Image to the desired representation and stores it internally.
   // The returned result is a weak pointer owned by and scoped to the life of
   // the Image.
+  const ImagePNG* ToImagePNG() const;
   const SkBitmap* ToSkBitmap() const;
   const ImageSkia* ToImageSkia() const;
 #if defined(TOOLKIT_GTK)
@@ -113,6 +120,7 @@ class UI_EXPORT Image {
   // backing pixels are shared amongst all copies (a fact of each of the
   // converted representations, rather than a limitation imposed by Image) and
   // so the result should be considered immutable.
+  ImagePNG* CopyImagePNG() const;
   ImageSkia* CopyImageSkia() const;
   SkBitmap* CopySkBitmap() const;
 #if defined(TOOLKIT_GTK)