Gtk3: Fix black patches on GtkFileChooser dialogs

chrome/browser/ui/libgtkui/gtk_util.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_LIBGTKUI_GTK_UTIL_H_
 #define CHROME_BROWSER_UI_LIBGTKUI_GTK_UTIL_H_
 
 #include <gtk/gtk.h>
 #include <string>
 
@@ skipping 156 matching lines @@
 SkColor GetFgColorFromStyleContext(GtkStyleContext* context);
 
 // Overrides properties on |context| and all its parents with those
 // provided by |css|.
 void ApplyCssToContext(GtkStyleContext* context, const std::string& css);
 
 // Get the 'color' property from the style context created by
 // GetStyleContextFromCss(|css_selector|).
 SkColor GetFgColor(const std::string& css_selector);
 
+ScopedCssProvider GetCssProvider(const std::string& css);
+
 // Renders the backgrounds of all ancestors of |context|, then renders
 // the background for |context| itself.
 void RenderBackground(const gfx::Size& size,
                       cairo_t* cr,
                       GtkStyleContext* context);
 
 // Renders a background from the style context created by
 // GetStyleContextFromCss(|css_selector|) into a 24x24 bitmap and
 // returns the average color.
 SkColor GetBgColor(const std::string& css_selector);
 
 // Renders the border from the style context created by
 // GetStyleContextFromCss(|css_selector|) into a 24x24 bitmap and
 // returns the average color.
 SkColor GetBorderColor(const std::string& css_selector);
 
 // On Gtk3.20 or later, behaves like GetBgColor.  Otherwise, returns
 // the background-color property.
 SkColor GetSelectionBgColor(const std::string& css_selector);
 
 // Get the color of the GtkSeparator specified by |css_selector|.
 SkColor GetSeparatorColor(const std::string& css_selector);
 #endif
 
 }  // namespace libgtkui
 
 #endif  // CHROME_BROWSER_UI_LIBGTKUI_GTK_UTIL_H_