bz informs me that nsIChannels are often kept around for a long time (for example, nsDocument holds on to its channel in perpetuity so it can get stuff like HTTP headers and whatnot as needed). Right now keeping a reference to an HttpChannelChild results in the entire IPDL protocol being kept alive, including the HttpChannelParent/nsHttpChannel in chrome. This is a waste of resources. We should be able to close down the IPDL channel and free the HttpChannelParent/nsHttpChannel after HttpChannelChild delivers OnStopRequest to its listener. nsDocument should have everything it needs from the HttpChannelChild. If we do this we should get rid of the the current PHttpChannel.ipdl "OnStopRequestCompleted" message, which is being used now only to free the cache descriptor. We would be sending __delete__ at the same time as that msg is currently called, and we could do the work in ~HttpChannelParent().

This has been fixed by bug 572980, which subsumed this.