ExtensionInfobarGtk doesn't handle delegate going away.

chrome/browser/ui/gtk/infobars/extension_infobar_gtk.h

Index: chrome/browser/ui/gtk/infobars/extension_infobar_gtk.h
diff --git a/chrome/browser/ui/gtk/infobars/extension_infobar_gtk.h b/chrome/browser/ui/gtk/infobars/extension_infobar_gtk.h
index a916d81f5dd75042a03995ff0786e5ce3f2cd99f..fb302f04f4c037f3f2443c6ef465a7239a1812c8 100644
--- a/chrome/browser/ui/gtk/infobars/extension_infobar_gtk.h
+++ b/chrome/browser/ui/gtk/infobars/extension_infobar_gtk.h
@@ -18,7 +18,8 @@ class ExtensionViewGtk;
 class MenuGtk;
 
 class ExtensionInfoBarGtk : public InfoBarGtk,
-                            public MenuGtk::Delegate {
+                            public MenuGtk::Delegate,
+                            public ExtensionInfoBarDelegate::DelegateObserver {
  public:
   ExtensionInfoBarGtk(InfoBarService* owner,
                       ExtensionInfoBarDelegate* delegate);
@@ -36,6 +37,9 @@ class ExtensionInfoBarGtk : public InfoBarGtk,
   // Overridden from MenuGtk::Delegate:
   virtual void StoppedShowing() OVERRIDE;
 
+  // Overridden from ExtensionInfoBarDelegate::DelegateObserver:
+  virtual void OnDelegateDeleted() OVERRIDE;
+
  private:
   // Build the widgets of the Infobar.
   void BuildWidgets();