ResizingHostObserver is created by the desktop environment together with other stubs.

remoting/host/host_status_observer.h

 // Copyright (c) 2012 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 REMOTING_HOST_HOST_STATUS_OBSERVER_H_
 #define REMOTING_HOST_HOST_STATUS_OBSERVER_H_
 
 #include <string>
 
 #include "third_party/skia/include/core/SkRect.h"
@@ skipping 28 matching lines @@
 
   // An authenticated client is disconnected.
   virtual void OnClientDisconnected(const std::string& jid) {}
 
   // Called on notification of a route change event, when a channel is
   // connected.
   virtual void OnClientRouteChange(const std::string& jid,
                                    const std::string& channel_name,
                                    const protocol::TransportRoute& route) {}
 
-  // Called when the client view size or pixel density change.
-  virtual void OnClientResolutionChanged(const std::string& jid,
-                                         const SkISize& size,
-                                         const SkIPoint& dpi) {}
-
   // Called when hosting is started for an account.
   virtual void OnStart(const std::string& xmpp_login) {}
 
   // Called when the host shuts down.
   virtual void OnShutdown() {}
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_HOST_STATUS_OBSERVER_H_