Mus: Delete unused Mandoline Surfaces code

components/mus/ws/server_window_delegate.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_WS_SERVER_WINDOW_DELEGATE_H_
 #define COMPONENTS_MUS_WS_SERVER_WINDOW_DELEGATE_H_
 
 #include <memory>
 
 #include "components/mus/public/interfaces/mus_constants.mojom.h"
@@ skipping 17 matching lines @@
 
   // Returns the root of the window tree to which this |window| is attached.
   // Returns null if this window is not attached up through to a root window.
   virtual const ServerWindow* GetRootWindow(
       const ServerWindow* window) const = 0;
 
   // Schedules a callback to DestroySurfacesScheduledForDestruction() at the
   // appropriate time, which may be synchronously.
   virtual void ScheduleSurfaceDestruction(ServerWindow* window) = 0;
 
-  // Used to resolve a reference to a Window by ClientWindowId in submitted
-  // frames. When the client owning |ancestor| (or the client embedded at
-  // |ancestor|) submits a frame the frame may referenced child windows. The
-  // reference is done using an id that is only known to the client. This
-  // function resolves the id into the appropriate window, or null if a window
-  // can't be found.
-  virtual ServerWindow* FindWindowForSurface(
-      const ServerWindow* ancestor,
-      mojom::SurfaceType surface_type,
-      const ClientWindowId& client_window_id) = 0;
-
  protected:
   virtual ~ServerWindowDelegate() {}
 };
 
 }  // namespace ws
 
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_WS_SERVER_WINDOW_DELEGATE_H_