Aura/GTK integration: Create a small stub library that can talk to GTK.

chrome/browser/ui/libgtk2ui/skia_utils_gtk2.cc

Index: chrome/browser/ui/libgtk2ui/skia_utils_gtk2.cc
diff --git a/chrome/browser/ui/libgtk2ui/skia_utils_gtk2.cc b/chrome/browser/ui/libgtk2ui/skia_utils_gtk2.cc
new file mode 100644
index 0000000000000000000000000000000000000000..140a87a6820419ef6cb8df64cbad926131b31640
--- /dev/null
+++ b/chrome/browser/ui/libgtk2ui/skia_utils_gtk2.cc
@@ -0,0 +1,32 @@
+// Copyright (c) 2011 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.
+
+#include "chrome/browser/ui/libgtk2ui/skia_utils_gtk2.h"
+
+#include <gdk/gdk.h>
+
+namespace libgtk2ui {
+
+const int kSkiaToGDKMultiplier = 257;
+
+// GDK_COLOR_RGB multiplies by 257 (= 0x10001) to distribute the bits evenly
+// See: http://www.mindcontrol.org/~hplus/graphics/expand-bits.html
+// To get back, we can just right shift by eight
+// (or, formulated differently, i == (i*257)/256 for all i < 256).
+
+SkColor GdkColorToSkColor(GdkColor color) {
+  return SkColorSetRGB(color.red >> 8, color.green >> 8, color.blue >> 8);
+}
+
+GdkColor SkColorToGdkColor(SkColor color) {
+  GdkColor gdk_color = {
+      0,
+      SkColorGetR(color) * kSkiaToGDKMultiplier,
+      SkColorGetG(color) * kSkiaToGDKMultiplier,
+      SkColorGetB(color) * kSkiaToGDKMultiplier
+  };
+  return gdk_color;
+}
+
+}  // namespace libgtk2ui