cros: add fingerprint latency UMA

biod collects some metrics that aren't taken care of by Chrome (see
CL:1166462) for the Chrome-side metrics.
Specifically biod knows about the capture/matching latency. We also add
the number of fingers that have been enrolled as it's more readily
accessible to biod than it is to Chrome.

The corresponding Chrome OS CL is CL:1173770

R=xiaoyinh

Bug: 862295
Change-Id: I8ae56d278fd9af4494bb969e7ff6e8bb336ad2bb
Reviewed-on: https://chromium-review.googlesource.com/1175458
Reviewed-by: Steven Holte <[email protected]>
Commit-Queue: Nicolas Norvez <[email protected]>
Cr-Commit-Position: refs/heads/master@{#583446}
1 file changed