Gtk3: Fix background colors

chrome/browser/ui/libgtkui/gtk_util.cc

 // Copyright (c) 2012 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/libgtkui/gtk_util.h"
 
 #include <dlfcn.h>
 #include <gdk/gdk.h>
 #include <gdk/gdkx.h>
 #include <gtk/gtk.h>
@@ skipping 376 matching lines @@
   // Get the color value of the single pixel.
   SkColor GetPixelValue() {
     return *reinterpret_cast<SkColor*>(cairo_image_surface_get_data(surface_));
   }
 
  private:
   cairo_surface_t* surface_;
   cairo_t* cairo_;
 };
 
+void RenderBackground(cairo_t* cr, GtkStyleContext* context) {
+  if (!context)
+    return;
+  RenderBackground(cr, gtk_style_context_get_parent(context));
+  gtk_render_background(context, cr, 0, 0, 1, 1);
+}
+
 SkColor GetBgColor(const char* css_selector) {
   // Backgrounds are more general than solid colors (eg. gradients),
   // but chromium requires us to boil this down to one color.  We
   // cannot use the background-color here because some themes leave it
   // set to a garbage color because a background-image will cover it
   // anyway.  So we instead render the background into a single pixel,
   // removing any borders, and hope that we get a good color.
   auto context = GetStyleContextFromCss(css_selector);
   RemoveBorders(context);
   PixelSurface surface;
-  gtk_render_background(context, surface.cairo(), 0, 0, 1, 1);
+  RenderBackground(surface.cairo(), context);
   return surface.GetPixelValue();
 }
 
 SkColor GetBorderColor(const char* css_selector) {
   // Borders have the same issue as backgrounds, due to the
   // border-image property.
   auto context = GetStyleContextFromCss(css_selector);
   GtkStateFlags state = gtk_style_context_get_state(context);
   GtkBorderStyle border_style = GTK_BORDER_STYLE_NONE;
   gtk_style_context_get(context, state, GTK_STYLE_PROPERTY_BORDER_STYLE,
                         &border_style, nullptr);
   GtkBorder border;
   gtk_style_context_get_border(context, state, &border);
   if ((border_style == GTK_BORDER_STYLE_NONE ||
        border_style == GTK_BORDER_STYLE_HIDDEN) ||
       (!border.left && !border.right && !border.top && !border.bottom)) {
     return SK_ColorTRANSPARENT;
   }
 
   AddBorders(context);
   PixelSurface surface;
+  RenderBackground(surface.cairo(), context);
   gtk_render_frame(context, surface.cairo(), 0, 0, 1, 1);
   return surface.GetPixelValue();
 }
 #endif
 
 }  // namespace libgtkui