Download/extract for libchromiumcontent doesn't detect failure; requires complete re-download of 3+ gigs

[Qix-]

This is minor, but annoying and should be something simple (I can't immediate see where in the script it's doing this check or else I would have submitted a PR).

When downloading the multi-gigabyte archive for libchromiumcontent, if the extraction fails, the whole bootstrap process fails, and when the whole bootstrap process fails brightray doesn't seem to notice that 1) the archive was not successfully extracted and 2) that the archive has already been downloaded and should just be extracted.

Instead, I have to remove the libchromiumcontent directory and start the download process over again.

Could we add a check for this? I just finished downloading it all and as it was extracting my primary drive ran out of space. Upon clearing some up, I ran the bootstrapper again for good measure and noticed it didn't start the extraction process over again.

So while it is downloading I figured I'd make a ticket about it :)