Another attempt at landing this patch....

chrome/plugin/webplugin_proxy.cc

Index: chrome/plugin/webplugin_proxy.cc
===================================================================
--- chrome/plugin/webplugin_proxy.cc	(revision 22262)
+++ chrome/plugin/webplugin_proxy.cc	(working copy)
@@ -287,8 +287,10 @@
 
 WebPluginResourceClient* WebPluginProxy::GetResourceClient(int id) {
   ResourceClientMap::iterator iterator = resource_clients_.find(id);
+  // The IPC messages which deal with streams are now asynchronous. It is
+  // now possible to receive stream messages from the renderer for streams
+  // which may have been cancelled by the plugin.
   if (iterator == resource_clients_.end()) {
-    NOTREACHED();
     return NULL;
   }
 
@@ -653,6 +655,10 @@
                                                   notify_needed, notify_data));
 }
 
+void WebPluginProxy::SetDeferResourceLoading(int resource_id, bool defer) {
+  Send(new PluginHostMsg_DeferResourceLoading(route_id_, resource_id, defer));
+}
+
 void WebPluginProxy::OnPaint(const gfx::Rect& damaged_rect) {
   child_process_logging::ScopedActiveURLSetter url_setter(page_url_);