Add support for PNG representation in gfx::Image

ui/gfx/image/image_png.h

Index: ui/gfx/image/image_png.h
diff --git a/ui/gfx/image/image_png.h b/ui/gfx/image/image_png.h
new file mode 100644
index 0000000000000000000000000000000000000000..cdada201ee7fe8b554e23b305b4f6cdc2a29fe86
--- /dev/null
+++ b/ui/gfx/image/image_png.h
@@ -0,0 +1,47 @@
+// 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_PNG_H_
+#define UI_GFX_IMAGE_IMAGE_PNG_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted_memory.h"
+#include "ui/base/ui_export.h"
+
+namespace gfx {
+
+// ImagePNG is a simple container for png-encoded data. It is cheap to copy
+// and intentionally supports copy semantics.
+class UI_EXPORT ImagePNG {

[Robert Sesek, 2012/07/19 23:45:07]

Why do we need ImagePNG? I think everything can be on gfx::Image with an
internal rep for the PNG bytes. Just have a constructor for Image(const unsigned
char* input, size_t input) and internally store that as a vector of the data.
The Copy/To methods can be implemented with the vector of bytes.

[cjhopman, 2012/07/20 17:28:24]

Done. Yeah, that works for me, we don't need ImagePNG.

+ public:
+  // Creates an ImagePNG from a copy of the png-encoded input.
+  explicit ImagePNG(const std::vector<unsigned char>& input);
+  ImagePNG(const unsigned char* input, size_t input_size);
+
+  // Copies a reference to |other|'s storage.
+  ImagePNG(const ImagePNG& other);
+
+  // Copies a reference to |other|'s storage.
+  ImagePNG& operator=(const ImagePNG& other);
+
+  ~ImagePNG();
+
+  static ImagePNG FromSkBitmap(const SkBitmap* bitmap);
+
+  bool empty() const;
+
+  const std::vector<unsigned char>& Image() const;
+ private:
+  // Default constructor only used by FromSkBitmap
+  ImagePNG();
+
+  // A refptr so that ImagePNG can be copied cheaply.
+  scoped_refptr<base::RefCountedBytes> image_;
+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_IMAGE_IMAGE_SKIA_H_