[gtk] fix theming of content settings bubble

chrome/browser/ui/gtk/gtk_theme_service.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_GTK_GTK_THEME_SERVICE_H_
 #define CHROME_BROWSER_UI_GTK_GTK_THEME_SERVICE_H_
 
 #include <map>
 #include <vector>
 
@@ skipping 77 matching lines @@
   // away.
   GtkWidget* BuildChromeButton();
 
   // Creates a GtkChromeLinkButton instance. We update its state as theme
   // changes, and listen for its destruction.
   GtkWidget* BuildChromeLinkButton(const std::string& text);
 
   // Builds a GtkLabel that is |color| in chrome theme mode, and the normal
   // text color in gtk-mode. Like the previous two calls, listens for the
   // object's destruction.
-  GtkWidget* BuildLabel(const std::string& text, GdkColor color);
+  GtkWidget* BuildLabel(const std::string& text, const GdkColor& color);
 
   // Creates a theme-aware vertical separator widget.
   GtkWidget* CreateToolbarSeparator();
 
   // A wrapper around ui::ThemeProvider::GetColor, transforming the result to a
   // GdkColor.
   GdkColor GetGdkColor(int id) const;
 
   // A weighted average between the text color and the background color of a
   // label. Used for borders between GTK stuff and the webcontent.
@@ skipping 189 matching lines @@
 
   // The default folder icon and default bookmark icon for the GTK theme.
   // These are static because the system can only have one theme at a time.
   // They are cached when they are requested the first time, and cleared when
   // the system theme changes.
   static base::LazyInstance<gfx::Image> default_folder_icon_;
   static base::LazyInstance<gfx::Image> default_bookmark_icon_;
 };
 
 #endif  // CHROME_BROWSER_UI_GTK_GTK_THEME_SERVICE_H_