Remove redundancy in security interstitial UMA logic

chrome/chrome_browser.gypi

 # Copyright 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.
 
 {
   'variables': {
     # All .cc, .h, .m, and .mm files under browser except for:
     # * tests and mocks.
     # * code below browser/chromeos
     # * code below browser/extensions
@@ skipping 400 matching lines @@
       'browser/install_verification/win/module_ids.h',
       'browser/install_verification/win/module_info.h',
       'browser/install_verification/win/module_list.cc',
       'browser/install_verification/win/module_list.h',
       'browser/install_verification/win/module_verification_common.cc',
       'browser/install_verification/win/module_verification_common.h',
       'browser/internal_auth.cc',
       'browser/internal_auth.h',
       'browser/interstitials/security_interstitial_page.cc',
       'browser/interstitials/security_interstitial_page.h',
+      'browser/interstitials/security_interstitial_uma_helper.cc',
+      'browser/interstitials/security_interstitial_uma_helper.h',
       'browser/intranet_redirect_detector.cc',
       'browser/intranet_redirect_detector.h',
       'browser/invalidation/invalidation_service_factory_android.cc',
       'browser/invalidation/invalidation_service_factory_android.h',
       'browser/invalidation/profile_invalidation_provider_factory.cc',
       'browser/invalidation/profile_invalidation_provider_factory.h',
       'browser/io_thread.cc',
       'browser/io_thread.h',
       'browser/jumplist_updater_win.cc',
       'browser/jumplist_updater_win.h',
@@ skipping 3281 matching lines @@
           'variables': {
             'proto_in_dir': 'browser/sync_file_system/drive_backend',
             'proto_out_dir': 'chrome/browser/sync_file_system/drive_backend',
           },
           'includes': [ '../build/protoc.gypi' ]
         },
       ],
     },],
   ],
 }