Revert r21117 as it caused reliability failures....

chrome/renderer/webplugin_delegate_proxy.cc

 // Copyright (c) 2006-2008 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.
 
 #include "chrome/renderer/webplugin_delegate_proxy.h"
 
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <atlbase.h>
@@ skipping 219 matching lines @@
     // case, don't try to connect to it, the empty name represents the host
     // channel, and connecting to it again does bad things.
     return false;
   }
 
   // If we received a ChannelHandle, register it now.
   if (channel_handle.socket.fd >= 0)
     IPC::AddChannelSocket(channel_handle.name, channel_handle.socket.fd);
 #endif
 
+  MessageLoop* ipc_message_loop = RenderThread::current()->owner_loop();
   scoped_refptr<PluginChannelHost> channel_host =
-      PluginChannelHost::GetPluginChannelHost(
-          channel_handle.name, ChildProcess::current()->io_message_loop());
+      PluginChannelHost::GetPluginChannelHost(channel_handle.name,
+                                              ipc_message_loop);
   if (!channel_host.get())
     return false;
 
   int instance_id;
   bool result = channel_host->Send(new PluginMsg_CreateInstance(
       mime_type_, &instance_id));
   if (!result)
     return false;
 
   plugin_path_ = plugin_path;
@@ skipping 757 matching lines @@
   plugin_->CancelDocumentLoad();
 }
 
 void WebPluginDelegateProxy::OnInitiateHTTPRangeRequest(
     const std::string& url, const std::string& range_info,
     intptr_t existing_stream, bool notify_needed, intptr_t notify_data) {
   plugin_->InitiateHTTPRangeRequest(url.c_str(), range_info.c_str(),
                                     existing_stream, notify_needed,
                                     notify_data);
 }