Use InterstitialPage through a delegate interface instead of deriving from it.

chrome/chrome_browser.gypi

 # 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.
 
 {
   'targets': [
     {
       'target_name': 'browser',
       'type': 'static_library',
       'variables': { 'enable_wexit_time_destructors': 1, },
@@ skipping 2370 matching lines @@
         'browser/sync/sync_ui_util.h',
         'browser/sync/sync_ui_util_mac.h',
         'browser/sync/sync_ui_util_mac.mm',
         'browser/sync/user_selectable_sync_type.h',
         'browser/tab_closeable_state_watcher.cc',
         'browser/tab_closeable_state_watcher.h',
         'browser/tab_first_render_watcher.cc',
         'browser/tab_first_render_watcher.h',
         'browser/tab_contents/background_contents.cc',
         'browser/tab_contents/background_contents.h',
-        'browser/tab_contents/chrome_interstitial_page.cc',
-        'browser/tab_contents/chrome_interstitial_page.h',
         'browser/tab_contents/chrome_tab_contents_view_wrapper_gtk.cc',
         'browser/tab_contents/chrome_tab_contents_view_wrapper_gtk.h',
         'browser/tab_contents/chrome_web_contents_view_mac_delegate.h',
         'browser/tab_contents/chrome_web_contents_view_mac_delegate.mm',
         'browser/tab_contents/confirm_infobar_delegate.cc',
         'browser/tab_contents/confirm_infobar_delegate.h',
         'browser/tab_contents/insecure_content_infobar_delegate.cc',
         'browser/tab_contents/insecure_content_infobar_delegate.h',
         'browser/tab_contents/language_state.cc',
         'browser/tab_contents/language_state.h',
@@ skipping 3111 matching lines @@
       'type': 'static_library',
       'sources': [ 'browser/history/in_memory_url_index_cache.proto' ],
       'variables': {
         'proto_in_dir': 'browser/history',
         'proto_out_dir': 'chrome/browser/history',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ],
 }