Create native_viewport_service, don't build it into mojo_shell unless Android

mojo/services/view_manager/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("//mojo/system.gni")
 
 # GYP version: mojo/mojo_services.gypi:mojo_view_manager
 component("view_manager") {
   deps = [
     "//base",
@@ skipping 54 matching lines @@
     "//base/test:test_support",
     "//mojo/application",
     "//mojo/application_manager",
     "//mojo/environment:chromium",
     "//mojo/services/public/cpp/input_events",
     "//mojo/services/public/cpp/geometry",
     "//mojo/services/public/cpp/view_manager",
     "//mojo/services/public/cpp/view_manager/lib:run_unittests",
     "//mojo/services/public/cpp/view_manager:common",
     "//mojo/services/public/interfaces/input_events",
+    "//mojo/services/public/interfaces/native_viewport",
     "//mojo/services/public/interfaces/geometry",
     "//mojo/services/public/interfaces/view_manager",
     "//mojo/shell:test_support",
     "//mojo/system",
     "//testing/gtest",
   ]
 
   sources = [
     "test_change_tracker.cc",
     "test_change_tracker.h",
     "view_manager_unittest.cc",
   ]
 }