Fix a crash related to PPAPI scripting.

webkit/plugins/ppapi/message_channel.h

Index: webkit/plugins/ppapi/message_channel.h
diff --git a/webkit/plugins/ppapi/message_channel.h b/webkit/plugins/ppapi/message_channel.h
index 1555b9002fd355b83fc7228765abdb2553291641..12f4c0b7c3c8935021339ef43f63e3fa60007cb0 100644
--- a/webkit/plugins/ppapi/message_channel.h
+++ b/webkit/plugins/ppapi/message_channel.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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.
 
@@ -42,7 +42,7 @@ class MessageChannel {
     MessageChannelNPObject();
     ~MessageChannelNPObject();
 
-    MessageChannel* message_channel;
+    base::WeakPtr<MessageChannel> message_channel;
   };
 
   explicit MessageChannel(PluginInstance* instance);