infobars: Remove the downcast AsAlternateNavInfoBarDelegate() function.

chrome/browser/api/infobars/infobar_delegate.cc

 // 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.
 
 #include "chrome/browser/api/infobars/infobar_delegate.h"
 
 #include "base/logging.h"
 #include "build/build_config.h"
 #include "chrome/browser/api/infobars/infobar_service.h"
 #include "content/public/browser/navigation_controller.h"
@@ skipping 29 matching lines @@
 }
 
 gfx::Image* InfoBarDelegate::GetIcon() const {
   return NULL;
 }
 
 InfoBarDelegate::Type InfoBarDelegate::GetInfoBarType() const {
   return WARNING_TYPE;
 }
 
-AlternateNavInfoBarDelegate* InfoBarDelegate::AsAlternateNavInfoBarDelegate() {
-  return NULL;
-}
-
 AutoLoginInfoBarDelegate* InfoBarDelegate::AsAutoLoginInfoBarDelegate() {
   return NULL;
 }
 
 ConfirmInfoBarDelegate* InfoBarDelegate::AsConfirmInfoBarDelegate() {
   return NULL;
 }
 
 ExtensionInfoBarDelegate* InfoBarDelegate::AsExtensionInfoBarDelegate() {
   return NULL;
@@ skipping 48 matching lines @@
   return (contents_unique_id_ != details.entry->GetUniqueID()) ||
       (content::PageTransitionStripQualifier(
           details.entry->GetTransitionType()) ==
               content::PAGE_TRANSITION_RELOAD);
 }
 
 void InfoBarDelegate::RemoveSelf() {
   if (owner_)
     owner_->RemoveInfoBar(this);  // Clears |owner_|.
 }