Add type for testing to interstitials.

content/content_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.
 
 {
   'dependencies': [
     '../base/base.gyp:base_static',
     '../crypto/crypto.gyp:crypto',
     '../device/vibration/vibration.gyp:device_vibration',
     '../device/vibration/vibration.gyp:device_vibration_mojo_bindings',
@@ skipping 120 matching lines @@
       'public/browser/geolocation_provider.h',
       'public/browser/global_request_id.h',
       'public/browser/gpu_data_manager.h',
       'public/browser/gpu_data_manager_observer.h',
       'public/browser/histogram_fetcher.h',
       'public/browser/host_zoom_map.h',
       'public/browser/indexed_db_context.h',
       'public/browser/indexed_db_info.cc',
       'public/browser/indexed_db_info.h',
       'public/browser/interstitial_page.h',
+      'public/browser/interstitial_page_delegate.cc',
+      'public/browser/interstitial_page_delegate.h',
       'public/browser/invalidate_type.h',
       'public/browser/javascript_dialog_manager.cc',
       'public/browser/javascript_dialog_manager.h',
       'public/browser/load_from_memory_cache_details.cc',
       'public/browser/load_from_memory_cache_details.h',
       'public/browser/load_notification_details.h',
       'public/browser/local_storage_usage_info.cc',
       'public/browser/local_storage_usage_info.h',
       'public/browser/location_provider.h',
       'public/browser/media_capture_devices.h',
@@ skipping 1821 matching lines @@
         'browser/media/media_web_contents_observer.h',
       ],
     }],
     ['OS == "linux" and use_openssl==1', {
       'dependencies': [
         '../third_party/boringssl/boringssl.gyp:boringssl',
       ],
     }],
   ],
 }