Add a GDK_COLOR_RGB macro for constructing GdkColors.

base/gfx/gtk_util.h

 // Copyright (c) 2009 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 BASE_GFX_GTK_UTIL_H_
 #define BASE_GFX_GTK_UTIL_H_
 
 #include <vector>
 
 typedef struct _GdkPixbuf GdkPixbuf;
 typedef struct _GdkRegion GdkRegion;
 class SkBitmap;
 
+// Define a macro for creating GdkColors from RGB values.  This is a macro to
+// allow static construction of literals, etc.  Use this like:
+//   GdkColor white = GDK_COLOR_RGB(0xff, 0xff, 0xff);
+#define GDK_COLOR_RGB(r, g, b) {0, r * 257, g * 257, b * 257}
+
 namespace gfx {
 
 class Rect;
 
 // Modify the given region by subtracting the given rectangles.
 void SubtractRectanglesFromRegion(GdkRegion* region,
                                   const std::vector<gfx::Rect>& cutouts);
 
 // Convert and copy a SkBitmap to a GdkPixbuf.  NOTE: This is an expensive
 // operation, all of the pixels must be copied and their order swapped.
 GdkPixbuf* GdkPixbufFromSkBitmap(const SkBitmap* bitmap);
 
 }  // namespace gfx
 
 #endif  // BASE_GFX_GTK_UTIL_H_