bluetooth: Require frame to be connected for characteristic.readValue to succeed
Rejects characteristic.readValue if the frame is not connected or if
the frame disconnects during the operation.
The new adapter has a Health Thermometer service with a measurement interval
characteristic. We use this characteristic because it the only standard
characteristic that supports Read, Write and Notify.
Reconnection tests in follow up patch:
http://crrev.com/2438963002
BUG=
608538
Committed:
https://crrev.com/0d1db684a6570d46b61fa141bc37ac95f3a6876a
Cr-Commit-Position: refs/heads/master@{#427007}