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 14 matching lines @@
 class GtkSignalRegistrar;
 class MenuModel;
 }
 
 class InfoBarGtk : public InfoBar,
                    public content::NotificationObserver {
  public:
   InfoBarGtk(InfoBarService* owner, InfoBarDelegate* delegate);
   virtual ~InfoBarGtk();
 
+  // Must be called before we try to show the infobar.  Inits any widgets and
+  // related objects necessary.  This must be called only once during the
+  // infobar's life.
+  //
+  // 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();
+
   // Get the top level native GTK widget for this infobar.
   GtkWidget* widget();
 
   GdkColor GetBorderColor() const;
 
   // Returns the target height of the infobar if the bar is animating,
   // otherwise 0. We care about this number since we want to prevent
   // unnecessary renderer repaints while animating.
   int AnimatingHeight() const;
 
@@ skipping 85 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_