GTK: Make the gtk port compile with GTK_DISABLE_SINGLE_INCLUDES.

ui/gfx/skia_utils_gtk.cc

 // Copyright (c) 2010 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 "ui/gfx/skia_utils_gtk.h"
 
-#include <gdk/gdkcolor.h>
+#include <gdk/gdk.h>
 
 namespace gfx {
 
 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 gfx