Add UMA to track when the verbose status string is not shown

We're not able to reliably repro this bug so adding some tracking UMA
to help diagnose and track this occurance in the future.

Bug: 929412
Change-Id: I8847e33c66a2635d23f2a9f415a739491adc7368
Reviewed-on: https://chromium-review.googlesource.com/c/1461193
Commit-Queue: Robert Ogden <robertogden@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#631483}
3 files changed