Extract the element implementation logic to function mods in <webview>.

extensions/extensions.gypi

 # Copyright 2015 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': {
     'extensions_common_constants_sources': [
       'common/constants.cc',
       'common/constants.h',
     ],
@@ skipping 933 matching lines @@
       'renderer/resources/test_custom_bindings.js',
       'renderer/resources/uncaught_exception_handler.js',
       'renderer/resources/unload_event.js',
       'renderer/resources/utils.js',
       'renderer/resources/guest_view/app_view/app_view.js',
       'renderer/resources/guest_view/extension_options/extension_options.js',
       'renderer/resources/guest_view/extension_view/extension_view.js',
       'renderer/resources/guest_view/surface_view/surface_view.js',
       'renderer/resources/guest_view/web_view/web_view.js',
       'renderer/resources/guest_view/web_view/web_view_events.js',
+      'renderer/resources/guest_view/web_view/web_view_iframe.js',
       'renderer/resources/web_request_custom_bindings.js',
       'renderer/resources/web_request_internal_custom_bindings.js',
       'renderer/runtime_custom_bindings.cc',
       'renderer/runtime_custom_bindings.h',
       'renderer/safe_builtins.cc',
       'renderer/safe_builtins.h',
       'renderer/script_context.cc',
       'renderer/script_context.h',
       'renderer/script_context_set.cc',
       'renderer/script_context_set.h',
@@ skipping 82 matching lines @@
       'test/result_catcher.h',
       'test/test_content_utility_client.cc',
       'test/test_content_utility_client.h',
       'test/test_extensions_client.cc',
       'test/test_extensions_client.h',
       'test/test_permission_message_provider.cc',
       'test/test_permission_message_provider.h',
     ],
   },
 }