[Clean Skeleton] Migrate code to clean/

ios/chrome/browser/ui/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.
 
 import("//build/config/ios/rules.gni")
 
 source_set("ui_arc") {
   sources = [
     "network_activity_indicator_manager.h",
     "network_activity_indicator_manager.mm",
@@ skipping 439 matching lines @@
     "//ios/chrome/browser/tabs:tabs_internal",
     "//ios/chrome/browser/ui/omnibox:omnibox_internal",
     "//ios/chrome/browser/ui/toolbar",
     "//ios/chrome/test/base:perf_test_support",
     "//testing/gtest",
     "//third_party/ocmock",
     "//ui/base:test_support",
   ]
   libs = [ "UIKit.framework" ]
 }
-
-# Clean skeleton targets
-source_set("ui_clean_skeleton") {
-  sources = [
-    "ui_types.h",
-  ]
-
-  configs += [ "//build/config/compiler:enable_arc" ]
-}