Remove ash_unittests/mash_unittests from Windows build targets

ash/BUILD.gn

 # Copyright 2014 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/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 import("//ui/base/ui_features.gni")
 
+# Historical note: Ash shipped on Windows for a couple years to support
+# Windows 8 Metro mode. Windows support was removed in 2016.
+assert(is_chromeos)
 assert(use_aura)
 assert(enable_hidpi)
 
 component("ash") {
   sources = [
     "accelerators/accelerator_commands_aura.cc",
     "accelerators/accelerator_commands_aura.h",
     "accelerators/accelerator_controller_delegate_aura.cc",
     "accelerators/accelerator_controller_delegate_aura.h",
     "accelerators/accelerator_delegate.cc",
@@ skipping 1486 matching lines @@
   if (is_win) {
     configs -= [ "//build/config/win:console" ]
     configs += [ "//build/config/win:windowed" ]
     deps += [ "//sandbox" ]
   }
 
   if (is_chromeos) {
     deps += [ "//device/bluetooth" ]
   }
 }