FingerMetrics: Try to avoid crash.

When updating finger metrics, make sure we have a FingerState.  I'm
hopeful that this fixes a crash we see, but as I have no repro, I'm
not sure.

BUG=chromium:254786
TEST=unittests pass

Change-Id: I09a7027c47ae909dc5a4803dcffcd42e9d36eec1
Reviewed-on: https://gerrit.chromium.org/gerrit/66424
Reviewed-by: Charlie Mooney <charliemooney@chromium.org>
Tested-by: Andrew de los Reyes <adlr@chromium.org>
Commit-Queue: Andrew de los Reyes <adlr@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/167935
Reviewed-by: Andrew de los Reyes <adlr@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/168301
1 file changed