[iOS] Upstream web_controller_provider_impl.{h,mm}.

ios/public/provider/web/BUILD.gn

 # 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.
 
 source_set("web") {
   configs += [ "//build/config/compiler:enable_arc" ]
   sources = [
     "web_controller_provider.h",
     "web_controller_provider.mm",
+    "web_controller_provider_factory.h",
+    "web_controller_provider_factory.mm",
   ]
 
   deps = [
     "//base",
     "//ios/web",
     "//url",
   ]
 
   allow_circular_includes_from = [ "//ios/web" ]
 }