Add metrics to crostini installer.

Currently, there are a significant number of install failures we don't
have much visibility into, especially on low-powered devices. This CL
adds metrics for free disk space and time to install, and records
failures due to network flake in the correct bucket, to give us a
better understanding of this.

Change-Id: I34ce13eabb698a9962db3da8cfe76eb48e33c3b4
Bug: 953545
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1569369
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Reviewed-by: Nicholas Verne <nverne@chromium.org>
Commit-Queue: Fergus Dall <sidereal@google.com>
Auto-Submit: Fergus Dall <sidereal@google.com>
Cr-Commit-Position: refs/heads/master@{#652041}
3 files changed