Converts WindowTreeClientTest to be in terms of aura

ui/aura/mus/window_tree_client.h

 // 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.
 
 #ifndef UI_AURA_MUS_WINDOW_TREE_CLIENT_H_
 #define UI_AURA_MUS_WINDOW_TREE_CLIENT_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 97 matching lines @@
   void SetCanAcceptEvents(Id window_id, bool can_accept_events);
   void SetPredefinedCursor(WindowMus* window,
                            ui::mojom::Cursor old_cursor,
                            ui::mojom::Cursor new_cursor);
   void SetWindowTextInputState(WindowMus* window,
                                mojo::TextInputStatePtr state);
   void SetImeVisibility(WindowMus* window,
                         bool visible,
                         mojo::TextInputStatePtr state);
 
+  // Embeds a new client in |window|.
   void Embed(Window* window,
              ui::mojom::WindowTreeClientPtr client,
              uint32_t flags,
              const ui::mojom::WindowTree::EmbedCallback& callback);
 
   void AttachCompositorFrameSink(
       Id window_id,
       ui::mojom::CompositorFrameSinkType type,
       cc::mojom::MojoCompositorFrameSinkRequest compositor_frame_sink,
       cc::mojom::MojoCompositorFrameSinkClientPtr client);
@@ skipping 386 matching lines @@
   std::unique_ptr<DragDropControllerMus> drag_drop_controller_;
 
   base::WeakPtrFactory<WindowTreeClient> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeClient);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_MUS_WINDOW_TREE_CLIENT_H_