[CrOS Tether] Ensure that BleAdvertiser explicitly calls Unregister() on all advertisements after they are done being used.
The previous implementation relied on the BluetoothAdvertisement's destructor calling Unregister(), but there are some situations in which the BLE framework holds onto references to the advertisements, resulting in their destructors not being called. This fix explicitly calls Unregister() on each advertisement.
BUG=672263
Review-Url: https://codereview.chromium.org/2782743002
Cr-Commit-Position: refs/heads/master@{#460439}
3 files changed
