[New Tab Page] Change the mechanism to intercept online NTP errors

chrome/chrome_tests.gypi

 # Copyright 2013 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.
 {
   'variables': {
     'chrome_browser_extensions_test_support_sources': [
       # A list of sources which is shared between different browser tests.
       'browser/apps/app_browsertest_util.cc',
       'browser/apps/app_browsertest_util.h',
       'browser/extensions/browsertest_util.cc',
@@ skipping 464 matching lines @@
       'browser/ui/exclusive_access/fullscreen_controller_browsertest.cc',
       'browser/ui/find_bar/find_bar_host_browsertest.cc',
       'browser/ui/global_error/global_error_service_browsertest.cc',
       'browser/ui/login/login_prompt_browsertest.cc',
       'browser/ui/location_bar/location_bar_browsertest.cc',
       'browser/ui/native_window_tracker_browsertest.cc',
       'browser/ui/panels/panel_extension_browsertest.cc',
       'browser/ui/passwords/manage_passwords_test.cc',
       'browser/ui/pdf/pdf_browsertest.cc',
       'browser/ui/prefs/prefs_tab_helper_browsertest.cc',
+      'browser/ui/search/new_tab_page_interceptor_browsertest.cc',
       'browser/ui/settings_window_manager_browsertest.cc',
       'browser/ui/startup/startup_browser_creator_browsertest.cc',
       'browser/ui/sync/one_click_signin_bubble_links_delegate_browsertest.cc',
       'browser/ui/sync/profile_signin_confirmation_helper_browsertest.cc',
       'browser/ui/tab_modal_confirm_dialog_browsertest.cc',
       'browser/ui/tab_modal_confirm_dialog_browsertest.h',
       'browser/ui/toolbar/browser_actions_bar_browsertest.cc',
       'browser/ui/toolbar/browser_actions_bar_browsertest.h',
       'browser/ui/toolbar/test_toolbar_model.cc',
       'browser/ui/toolbar/test_toolbar_model.h',
@@ skipping 2758 matching lines @@
             ['enable_webrtc==1', {
               'dependencies': [
                 '../third_party/libjingle/libjingle.gyp:libjingle_webrtc'
               ]
             }],
           ],
         }]
     }],
   ],  # 'conditions'
 }