Revert of Deletes mojo::Callback

components/mus/ws/window_tree_client_unittest.cc

 // 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.
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/strings/stringprintf.h"
 #include "components/mus/public/cpp/tests/window_server_shelltest_base.h"
 #include "components/mus/public/interfaces/window_tree.mojom.h"
 #include "components/mus/public/interfaces/window_tree_host.mojom.h"
 #include "components/mus/ws/ids.h"
 #include "components/mus/ws/test_change_tracker.h"
 #include "mojo/public/cpp/bindings/associated_binding.h"
 #include "services/shell/public/cpp/shell_test.h"
 
 using mojo::Array;
+using mojo::Callback;
 using shell::Connection;
 using mojo::InterfaceRequest;
 using shell::ShellClient;
 using mojo::String;
 using mus::mojom::WindowDataPtr;
 using mus::mojom::WindowTree;
 using mus::mojom::WindowTreeClient;
 
 namespace mus {
 namespace ws {
@@ skipping 1999 matching lines @@
 
 // TODO(sky): make sure coverage of what was
 // WindowManagerTest.SecondEmbedRoot_InitService and
 // WindowManagerTest.MultipleEmbedRootsBeforeWTHReady gets added to window
 // manager
 // tests.
 
 }  // namespace test
 }  // namespace ws
 }  // namespace mus