Add InitWidgets() phase for GTK infobars.

chrome/browser/ui/gtk/infobars/infobar_gtk.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_INFOBARS_INFOBAR_GTK_H_
 #define CHROME_BROWSER_UI_GTK_INFOBARS_INFOBAR_GTK_H_
 
 #include <gtk/gtk.h>
 
 #include "base/basictypes.h"
@@ skipping 80 matching lines @@
   // InfoBar:
   virtual void PlatformSpecificShow(bool animate) OVERRIDE;
   virtual void PlatformSpecificOnCloseSoon() OVERRIDE;
   virtual void PlatformSpecificOnHeightsRecalculated() OVERRIDE;
 
   // content::NotificationObserver:
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
+  // Called the first time we try to show the infobar.  Inits any widgets and
+  // related objects necessary.
+  //
+  // NOTE: Subclasses who need to init widgets should override this function and
+  // explicitly call their parent's implementation first, then continue with
+  // further work they need to do.  Failing to call the parent implementation
+  // first (or at all), or setting up widgets in the constructor instead of
+  // here, will lead to bad side effects like crashing or having this function
+  // get called repeatedly.
+  virtual void InitWidgets();
+
   // The second highest widget in the hierarchy (after the |widget_|).
   GtkWidget* bg_box_;
 
   // The hbox that holds infobar elements (button, text, icon, etc.).
   GtkWidget* hbox_;
 
   // The x that closes the bar.
   scoped_ptr<CustomDrawButton> close_button_;
 
   // The theme provider, used for getting border colors.
@@ skipping 19 matching lines @@
   scoped_ptr<ui::GtkSignalRegistrar> signals_;
 
   // The current menu displayed. Can be null. We own this on the base class so
   // we can cancel the menu while we're closing.
   scoped_ptr<MenuGtk> menu_;
 
   DISALLOW_COPY_AND_ASSIGN(InfoBarGtk);
 };
 
 #endif  // CHROME_BROWSER_UI_GTK_INFOBARS_INFOBAR_GTK_H_