Removes some dead code from WindowTreeClient

components/mus/public/cpp/lib/window_tree_client_impl.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 COMPONENTS_MUS_PUBLIC_CPP_LIB_WINDOW_TREE_CLIENT_IMPL_H_
 #define COMPONENTS_MUS_PUBLIC_CPP_LIB_WINDOW_TREE_CLIENT_IMPL_H_
 
 #include <map>
 
 #include "base/observer_list.h"
@@ skipping 172 matching lines @@
                                        mojom::Cursor cursor) override;
   void OnChangeCompleted(uint32_t change_id, bool success) override;
   void WmSetBounds(uint32_t change_id,
                    Id window_id,
                    mojo::RectPtr transit_bounds) override;
   void WmSetProperty(uint32_t change_id,
                      Id window_id,
                      const mojo::String& name,
                      mojo::Array<uint8_t> transit_data) override;
 
-  mojo::Callback<void(bool)> ActionCompletedCallback();
-
   // This is set once and only once when we get OnEmbed(). It gives the unique
   // id for this connection.
   ConnectionSpecificId connection_id_;
 
   // Id assigned to the next window created.
   ConnectionSpecificId next_window_id_;
 
   // Id used for the next change id supplied to the server.
   uint32_t next_change_id_;
   InFlightMap in_flight_map_;
@@ skipping 19 matching lines @@
   bool in_destructor_;
 
   base::ObserverList<WindowTreeConnectionObserver> observers_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(WindowTreeClientImpl);
 };
 
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_PUBLIC_CPP_LIB_WINDOW_TREE_CLIENT_IMPL_H_