Add key modifier to minimize/restore button click to minimize/restore-all panels for GTK

chrome/browser/ui/gtk/browser_titlebar.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.
 //
 // A helper class that contains the gtk widgets that make up the titlebar.  The
 // titlebar consists of the tabstrip and if the custom chrome frame is turned
 // on, it includes the taller titlebar and minimize, restore, maximize, and
 // close buttons.
 
 #ifndef CHROME_BROWSER_UI_GTK_BROWSER_TITLEBAR_H_
@@ skipping 35 matching lines @@
 
   GtkWidget* widget() {
     return container_;
   }
 
   void set_window(GtkWindow* window) { window_ = window; }
 
   // Build the titlebar, the space above the tab strip, and (maybe) the min,
   // max, close buttons. |container_| is the gtk container that we put the
   // widget into.
-  void Init();
+  virtual void Init();
 
   // Builds the buttons based on the metacity |button_string|.
   void BuildButtons(const std::string& button_string);
 
   // Updates the theme supplied background color and image.
   void UpdateButtonBackground(CustomDrawButton* button);
 
   // Update the appearance of the title bar based on whether we're showing a
   // custom frame or not.  If |use_custom_frame| is true, we show an extra
   // tall titlebar and the min/max/close buttons.
@@ skipping 237 matching lines @@
   // The avatar button.
   scoped_ptr<AvatarMenuButtonGtk> avatar_button_;
 
   // Theme provider for building buttons.
   ThemeServiceGtk* theme_service_;
 
   content::NotificationRegistrar registrar_;
 };
 
 #endif  // CHROME_BROWSER_UI_GTK_BROWSER_TITLEBAR_H_