Let CRIWVWebView inherit UIView instead of NSObject.

ios/web_view/internal/BUILD.gn

 # Copyright 2016 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.
 
 source_set("internal") {
   visibility = [
     "//ios/web_view",
     "//ios/web_view/internal/*",
   ]
 
   sources = [
     "criwv.mm",
     "criwv_browser_state.h",
     "criwv_browser_state.mm",
     "criwv_network_delegate.cc",
     "criwv_network_delegate.h",
     "criwv_url_request_context_getter.h",
     "criwv_url_request_context_getter.mm",
     "criwv_web_client.h",
     "criwv_web_client.mm",
     "criwv_web_main_delegate.h",
     "criwv_web_main_delegate.mm",
     "criwv_web_main_parts.h",
     "criwv_web_main_parts.mm",
-    "criwv_web_view_impl.h",
-    "criwv_web_view_impl.mm",
+    "criwv_web_view.mm",
+    "criwv_web_view_internal.h",
     "pref_names.cc",
     "pref_names.h",
   ]
   deps = [
     "//base",
     "//components/pref_registry",
     "//components/prefs",
     "//components/translate/core/browser",
     "//components/translate/core/common",
     "//ios/net",
     "//ios/web",
     "//ios/web:user_agent",
     "//ios/web/public/app",
     "//ios/web_view/internal/translate",
     "//ios/web_view/public",
     "//net",
     "//net:extras",
     "//ui/base",
     "//url",
   ]
   allow_circular_includes_from = [ "//ios/web_view/internal/translate" ]
 }