sandbox/win: Fix warnings found by clang chromium-style plugin on Windows.

sandbox/win/src/crosscall_server.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 SANDBOX_SRC_CROSSCALL_SERVER_H_
 #define SANDBOX_SRC_CROSSCALL_SERVER_H_
 
 #include <string>
 #include <vector>
 #include "base/basictypes.h"
@@ skipping 189 matching lines @@
   // Called from the  IPC implementation when an  IPC message is ready override
   // on a derived class to handle a set of  IPC messages. Return NULL if your
   // subclass does not handle the message or return the pointer to the subclass
   // that can handle it.
   virtual Dispatcher* OnMessageReady(IPCParams* ipc, CallbackGeneric* callback);
 
   // Called when a target proces is created, to setup the interceptions related
   // with the given service (IPC).
   virtual bool SetupService(InterceptionManager* manager, int service) = 0;
 
-  virtual ~Dispatcher() {}
+  Dispatcher();
+  virtual ~Dispatcher();
 
  protected:
   // Structure that defines an IPC Call with all the parameters and the handler.
   struct IPCCall {
     IPCParams params;
     CallbackGeneric callback;
   };
 
   // List of IPC Calls supported by the class.
   std::vector<IPCCall> ipc_calls_;
 };
 
 }  // namespace sandbox
 
 #endif  // SANDBOX_SRC_CROSSCALL_SERVER_H_