Never lock the Pepper proxy lock on the IO thread

content/ppapi_plugin/ppapi_thread.cc

Index: content/ppapi_plugin/ppapi_thread.cc
diff --git a/content/ppapi_plugin/ppapi_thread.cc b/content/ppapi_plugin/ppapi_thread.cc
index 8b612fbe97b9d02238dd7c3f80952e2ece24479a..9608e192f2fb4e9c39b5f6fa88c5794951abc144 100644
--- a/content/ppapi_plugin/ppapi_thread.cc
+++ b/content/ppapi_plugin/ppapi_thread.cc
@@ -113,9 +113,11 @@ PpapiThread::PpapiThread(const base::CommandLine& command_line, bool is_broker)
   blink::initialize(blink_platform_impl_.get());
 
   if (!is_broker_) {
-    channel()->AddFilter(
+    scoped_refptr<ppapi::proxy::PluginMessageFilter> plugin_filter(
         new ppapi::proxy::PluginMessageFilter(
             NULL, globals->resource_reply_thread_registrar()));
+    channel()->AddFilter(plugin_filter.get());
+    globals->RegisterResourceMessageFilters(plugin_filter.get());

[raymes, 2015/03/03 03:07:44]

I guess both these add references?

[dmichael (off chromium), 2015/03/03 18:27:56]

This is a little confusing, and I struggled with how to organize this and name
stuff.

As it's organized in this patch, PluginGlobals knows about any special
plugin-side filters that need to be able to listen on the IO thread. In this
case, that's only UDPSocketFilter. There needs to be exactly one instance of
UDPSocketFilter, and it must be accessible from two places:
- UDPSocketResourceBase (for adding/removing itself and draining its message
queue)
- PluginMessageFilter has to be able to pass messages to it.

I chose to make PluginMessageFilter have no special knowledge about what
particular plugin filters there are. Instead, it asks PluginGlobals to add all
the filters that PluginGlobals knows about (see the implementation of
RegisterResourceMessageFilters).

So effectively, this is adding UDPSocketFilter to PluginMessageFilter's list of
ResourceMessageFilters.

PluginGlobals will not have a reference on PluginMessageFilter. On the other
hand, PluginMessageFilter and PluginGlobals *will* both have a reference on
UDPSocketFilter (maybe that's what you meant) 

   }
 }