[Extensions] Remove the Infobar API

components/infobars/core/infobar_delegate.cc

 // Copyright 2014 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 "components/infobars/core/infobar_delegate.h"
 
 #include "base/logging.h"
 #include "build/build_config.h"
 #include "components/infobars/core/infobar.h"
 #include "components/infobars/core/infobar_manager.h"
@@ skipping 34 matching lines @@
 }
 
 AutoLoginInfoBarDelegate* InfoBarDelegate::AsAutoLoginInfoBarDelegate() {
   return nullptr;
 }
 
 ConfirmInfoBarDelegate* InfoBarDelegate::AsConfirmInfoBarDelegate() {
   return nullptr;
 }
 
-ExtensionInfoBarDelegate* InfoBarDelegate::AsExtensionInfoBarDelegate() {
-  return nullptr;
-}
-
 InsecureContentInfoBarDelegate*
     InfoBarDelegate::AsInsecureContentInfoBarDelegate() {
   return nullptr;
 }
 
 MediaStreamInfoBarDelegate* InfoBarDelegate::AsMediaStreamInfoBarDelegate() {
   return nullptr;
 }
 
 NativeAppInfoBarDelegate* InfoBarDelegate::AsNativeAppInfoBarDelegate() {
@@ skipping 38 matching lines @@
 }
 
 bool InfoBarDelegate::ShouldExpireInternal(
     const NavigationDetails& details) const {
   // NOTE: If you change this, be sure to check and adjust the behavior of
   // anyone who overrides this as necessary!
   return (contents_unique_id_ != details.entry_id) || details.is_reload;
 }
 
 }  // namespace infobars