Make GetAppId() pure-virtual and add implementation for TCPSocketParent, UDPSocketParent, and one for Necko parent that returns UNKNOWN_APP_ID
Change nsIOService to use IsNeckoChild instead of XRE_ method.
Include nsThreadUtils.h (for nsRunnable and dispatchToMainThread) and NeckoCommon for IsNeckoChild.
Make HttpChannelParent set LOAD_ONLY_FROM_CACHE, LOAD_FROM_CACHE and LOAD_NO_NETWORK_IO when offline.