Make the exception for ExecuteScript a regular Var instead of a VarPrivate.

ppapi/cpp/private/instance_private.h

 // Copyright (c) 2011 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 PPAPI_CPP_PRIVATE_INSTANCE_PRIVATE_H_
 #define PPAPI_CPP_PRIVATE_INSTANCE_PRIVATE_H_
 
 /**
  * @file
  * Defines the API ...
@@ skipping 27 matching lines @@
   // @{
   /// @name PPB_Instance_Private methods for querying the browser:
 
   /// See PPB_Instance_Private.GetWindowObject.
   VarPrivate GetWindowObject();
 
   /// See PPB_Instance_Private.GetOwnerElementObject.
   VarPrivate GetOwnerElementObject();
 
   /// See PPB_Instance.ExecuteScript.
-  VarPrivate ExecuteScript(const Var& script, VarPrivate* exception = NULL);
+  VarPrivate ExecuteScript(const Var& script, Var* exception = NULL);
 
   // @}
 };
 
 }  // namespace pp
 
 /**
  * @}
  * End addtogroup CPP
  */
 #endif  // PPAPI_CPP_PRIVATE_INSTANCE_PRIVATE_H_