Remove base/win/metro.{cc|h} and some associated code

base/BUILD.gn

 # Copyright (c) 2013 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.
 
 # HOW TO WRITE CONDITIONALS IN THIS FILE
 # ======================================
 #
 # In many other places, one would write a conditional that expresses all the
 # cases when a source file is used or unused, and then either add or subtract
 # it from the sources list in that case
@@ skipping 886 matching lines @@
     "win/event_trace_provider.cc",
     "win/event_trace_provider.h",
     "win/i18n.cc",
     "win/i18n.h",
     "win/iat_patch_function.cc",
     "win/iat_patch_function.h",
     "win/iunknown_impl.cc",
     "win/iunknown_impl.h",
     "win/message_window.cc",
     "win/message_window.h",
-    "win/metro.cc",
-    "win/metro.h",
     "win/object_watcher.cc",
     "win/object_watcher.h",
     "win/process_startup_helper.cc",
     "win/process_startup_helper.h",
     "win/registry.cc",
     "win/registry.h",
     "win/resource_util.cc",
     "win/resource_util.h",
     "win/scoped_bstr.cc",
     "win/scoped_bstr.h",
@@ skipping 1223 matching lines @@
 
   # GYP: //base.gyp:base_java_unittest_support
   android_library("base_java_unittest_support") {
     deps = [
       ":base_java",
     ]
     java_files =
         [ "test/android/java/src/org/chromium/base/ContentUriTestUtils.java" ]
   }
 }