Chromium does not throw the exception message by calling NPN_SetException from NPAPI plugin

content/common/npobject_proxy.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.
 //
 // A proxy for NPObject that sends all calls to the object to an NPObjectStub
 // running in a different process.
 
 #ifndef CONTENT_COMMON_NPOBJECT_PROXY_H_
 #define CONTENT_COMMON_NPOBJECT_PROXY_H_
 #pragma once
@@ skipping 77 matching lines @@
                               NPVariant *result);
 
   static NPObjectProxy* GetProxy(NPObject* object);
   static const NPClass* npclass() { return &npclass_proxy_; }
 
   // NPObjectBase implementation.
   virtual NPObject* GetUnderlyingNPObject();
 
   virtual IPC::Channel::Listener* GetChannelListener();
 
+  bool HasExceptionThrown() const { return has_exception_thrown_; }
+
+  void SetExceptionThrown(bool has_thrown) {
+    has_exception_thrown_ = has_thrown;
+  }
+
  private:
   NPObjectProxy(NPChannelBase* channel,
                 int route_id,
                 gfx::NativeViewId containing_window,
                 const GURL& page_url);
 
   // IPC::Channel::Listener implementation:
   virtual bool OnMessageReceived(const IPC::Message& msg);
   virtual void OnChannelError();
+  virtual void OnSetException(const std::string& msg);
 
   static NPObject* NPAllocate(NPP, NPClass*);
   static void NPDeallocate(NPObject* npObj);
 
   // This function is only caled on NPObjects from the plugin.
   static void NPPInvalidate(NPObject *obj);
   static NPClass npclass_proxy_;
 
   scoped_refptr<NPChannelBase> channel_;
   int route_id_;
   gfx::NativeViewId containing_window_;
 
   // The url of the main frame hosting the plugin.
   GURL page_url_;
+
+  // Indicates whether an exception is set via NPN_SetException
+  // called from plugin
+  bool has_exception_thrown_;
 };
 
 #endif  // CONTENT_COMMON_NPOBJECT_PROXY_H_