This content is now available at https://wiki.unvanquished.net/wiki/Breakpad
The Breakpad repo for Daemon Engine is at https://github.com/DaemonEngine/breakpad. If you have already checked out Daemon, then it is located in the libs/breakpad/
submodule there. cd into this repo.
Daemon's Breakpad fork is based on https://github.com/jon-turney/google-breakpad, with only minor changes. Jon Turney's version adds MinGW support. It is in turn a fork of Chromium's Breakpad https://chromium.googlesource.com/breakpad/breakpad.