Windows updater: avoid writing to the Windows registry for "in use" files
This is a spinoff from ticket legacy/trac#16014 (moved).
On Windows, when the Mozilla updater encounters a file that is in use (which means it cannot be deleted), it moves the file to a "tobedeleted" directory and then uses a call like the following to arrange for it to be deleted the next time Windows is restarted:
MoveFileEx(path, nullptr, MOVEFILE_DELAY_UNTIL_REBOOT);
This works fine, but it would be better to avoid writing to the registry. We could fix this by adding code to nsUpdateService.js to make a "best effort" attempt to delete all files in the "tobedeleted" directory each time the browser is restarted.
Let's consider doing this for Tor Browser 5.