Restructure public side of view_manager service.

mojo/services/public/cpp/view_manager/tests/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/ui.gni")
-
-test("mojo_view_manager_lib_unittests") {
-  sources = [
-    "view_unittest.cc",
-    "view_manager_unittest.cc",
-  ]
-
-  deps = [
-    "//base",
-    "//base/test:test_support",
-    "//mojo/application_manager",
-    "//mojo/converters/geometry",
-    "//mojo/environment:chromium",
-    "//mojo/public/cpp/application",
-    "//mojo/services/public/cpp/geometry",
-    "//mojo/services/public/cpp/view_manager",
-    "//mojo/services/public/interfaces/geometry",
-    "//mojo/services/public/interfaces/view_manager",
-    "//shell:test_support",
-    "//testing/gtest",
-  ]
-  if (use_aura) {
-    deps += [ "//mojo/services/public/cpp/view_manager/lib:run_unittests" ]
-  } else {
-    deps += [ "//mojo/edk/test:run_all_unittests" ]
-  }
-}