Crosperf: Remove tar file after uncompressing image

Remove downloaded chromium image.tar.xz file after uncompression.
Change 2 step untar and uncompress to 1. Catch exceptions during
uncompression to avoid having a corrupted bin file if
uncompression is interrupted.

BUG: chromium:663426
TEST: crosperf unit tests pass
Change-Id: I82f674a26bf99cb3491e7db770664c73c004a93b
Reviewed-on: https://chrome-internal-review.googlesource.com/303875
Commit-Ready: Manoj Gupta <manojgupta@google.com>
Tested-by: Manoj Gupta <manojgupta@google.com>
Reviewed-by: Caroline Tice <cmtice@google.com>
2 files changed