I've been tasked with implementing electrolysis (e10s) support for FTP. That means letting child processes (content) send requests to the parent process (chrome), which actually does the networking - while from the perspective of the child process, the interface to an FTP channel is the same.
As this is just my second week at Mozilla, I am still learning the build process, fundamental technologies like XPCOM, and other stuff about the codebase. So I ran into some problems, which I'll mention here on the blog in hopes that they help other people that search for the same keywords.
So, lesson #1 is: Improper XPCOM definitions can lead to silent failure.
Specifically, the issue was that this: