Fix a crash related to PPAPI scripting.

ppapi/proxy/plugin_dispatcher.h

-// 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.
 
 #ifndef PPAPI_PROXY_PLUGIN_DISPATCHER_H_
 #define PPAPI_PROXY_PLUGIN_DISPATCHER_H_
 
 #include <set>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/hash_tables.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "base/process.h"
 #include "build/build_config.h"
 #include "ppapi/c/dev/ppb_console_dev.h"
 #include "ppapi/c/pp_rect.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/proxy/dispatcher.h"
 #include "ppapi/shared_impl/function_group_base.h"
 #include "ppapi/shared_impl/ppapi_preferences.h"
 #include "ppapi/shared_impl/ppb_view_shared.h"
 
@@ skipping 10 matching lines @@
   ~InstanceData();
 
   ViewData view;
 
   PP_Bool flash_fullscreen;  // Used for PPB_FlashFullscreen.
 
   // When non-0, indicates the callback to execute when mouse lock is lost.
   PP_CompletionCallback mouse_lock_callback;
 };
 
-class PPAPI_PROXY_EXPORT PluginDispatcher : public Dispatcher {
+class PPAPI_PROXY_EXPORT PluginDispatcher
+    : public Dispatcher,
+      public base::SupportsWeakPtr<PluginDispatcher> {
  public:
   class PPAPI_PROXY_EXPORT PluginDelegate : public ProxyChannel::Delegate {
    public:
     // Returns the set used for globally uniquifying PP_Instances. This same
     // set must be returned for all channels.
     //
     // DEREFERENCE ONLY ON THE I/O THREAD.
     virtual std::set<PP_Instance>* GetGloballySeenInstanceIDSet() = 0;
 
     // Registers the plugin dispatcher and returns an ID.
@@ skipping 101 matching lines @@
 
   uint32 plugin_dispatcher_id_;
 
   DISALLOW_COPY_AND_ASSIGN(PluginDispatcher);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_PLUGIN_DISPATCHER_H_