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

sandbox/win/src/crosscall_server.h

Index: sandbox/win/src/crosscall_server.h
diff --git a/sandbox/win/src/crosscall_server.h b/sandbox/win/src/crosscall_server.h
index e75400654120a672832f9436372736e93a97ca84..41888c1203c48f9181559a43ebb48f2641437198 100644
--- a/sandbox/win/src/crosscall_server.h
+++ b/sandbox/win/src/crosscall_server.h
@@ -207,7 +207,8 @@ class Dispatcher {
   // 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.