libgtk2ui: cast gdk_color components to fix compilation under gcc 4.7.2

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
index 726b70ab1f766233d3865f0fb1d890b7c8592609..44f03f5f2dff6db8fbd8611b6d49aee21190944d 100644
--- a/chrome/browser/ui/libgtk2ui/skia_utils_gtk2.cc
+++ b/chrome/browser/ui/libgtk2ui/skia_utils_gtk2.cc
@@ -22,9 +22,9 @@ SkColor GdkColorToSkColor(GdkColor color) {
 GdkColor SkColorToGdkColor(SkColor color) {
   GdkColor gdk_color = {
       0,
-      SkColorGetR(color) * kSkiaToGDKMultiplier,
-      SkColorGetG(color) * kSkiaToGDKMultiplier,
-      SkColorGetB(color) * kSkiaToGDKMultiplier
+      static_cast<guint16>(SkColorGetR(color) * kSkiaToGDKMultiplier),
+      static_cast<guint16>(SkColorGetG(color) * kSkiaToGDKMultiplier),
+      static_cast<guint16>(SkColorGetB(color) * kSkiaToGDKMultiplier)
   };
   return gdk_color;
 }