re-apply r34183...

chrome/browser/gtk/gtk_theme_provider.h

 // Copyright (c) 2009 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_GTK_GTK_THEME_PROVIDER_H_
 #define CHROME_BROWSER_GTK_GTK_THEME_PROVIDER_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 47 matching lines @@
   bool UseGtkTheme() const;
 
   // A wrapper around 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.
   GdkColor GetBorderColor() const;
 
+  // This method returns averages of the thumb part and of the track colors.
+  // Used when rendering scrollbars.
+  static void GetScrollbarColors(GdkColor* thumb_active_color,
+                                 GdkColor* thumb_inactive_color,
+                                 GdkColor* track_color,
+                                 bool use_gtk_theme);
+
   // Expose the inner label. Only used for testing.
   GtkWidget* fake_label() { return fake_label_.get(); }
 
   // Returns a CairoCachedSurface for a particular Display. CairoCachedSurfaces
   // (hopefully) live on the X server, instead of the client so we don't have
   // to send the image to the server on each expose.
   CairoCachedSurface* GetSurfaceNamed(int id, GtkWidget* widget_on_display);
 
   // These functions do not add a ref to the returned pixbuf, and it should not be
   // unreffed.
@@ skipping 68 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 GdkPixbuf* default_folder_icon_;
   static GdkPixbuf* default_bookmark_icon_;
 };
 
 #endif  // CHROME_BROWSER_GTK_GTK_THEME_PROVIDER_H_