CHROMIUM: Refine metrics for the adapter lost histogram

This changes the data type (the unit) of samples from number of occurrence
to duration (seconds) of not having adapter presented for the adapter lost
histogram. This also fixes an error on switch-case pass-through of
BlueZ.TimeLengthOfSetupConnection histogram.

BUG=chromium:777981
TEST=For adapter lost, drop the controller manually to mimic the adapter lost.
For connection duration, connect a BLE keyboard. And check
chrome://histograms page to make sure the expected samples were emitted.

Change-Id: Id1f86e08ff779c090f2d5991d4e594296dc38130
Reviewed-on: https://chromium-review.googlesource.com/784291
Commit-Ready: Miao-chen Chou <mcchou@chromium.org>
Tested-by: Miao-chen Chou <mcchou@chromium.org>
Reviewed-by: Shyh-In Hwang <josephsih@chromium.org>
3 files changed