Native themes: Add menu separator part

chrome/browser/ui/libgtkui/gtk_util.cc

Index: chrome/browser/ui/libgtkui/gtk_util.cc
diff --git a/chrome/browser/ui/libgtkui/gtk_util.cc b/chrome/browser/ui/libgtkui/gtk_util.cc
index 543cbda3c6e104f0e0869726f3e6cc35a99c86cf..55bd85f9299118c1c9a8a3f18ae1cff06eed298c 100644
--- a/chrome/browser/ui/libgtkui/gtk_util.cc
+++ b/chrome/browser/ui/libgtkui/gtk_util.cc
@@ -347,14 +347,17 @@ SkColor GdkRgbaToSkColor(const GdkRGBA& color) {
                         color.blue * 255);
 }
 
-SkColor GetFgColor(const char* css_selector) {
-  auto context = GetStyleContextFromCss(css_selector);
+SkColor SkColorFromStyleContext(GtkStyleContext* context) {
   GdkRGBA color;
   gtk_style_context_get_color(context, gtk_style_context_get_state(context),
                               &color);
   return GdkRgbaToSkColor(color);
 }
 
+SkColor GetFgColor(const char* css_selector) {
+  return SkColorFromStyleContext(GetStyleContextFromCss(css_selector));
+}
+
 GtkCssProvider* GetCssProvider(const char* css) {
   GtkCssProvider* provider = gtk_css_provider_new();
   GError* error = nullptr;