Bluetooth: implement bluetooth_Sanity_Discoverable

This test is the first example of a Bluetooth test with a separate
tester device (a stumpy with the testbed-ap profile is the intent).
It can be run two ways:

 1. as bluetooth_Sanity_Discoverable - in which case the Tester will
    be used to perform a device discovery and verify that the DUT
    was detected in the process.

 2. as bluetooth_Sanity_Discoverable.manual - in which case only the
    DUT is used, and instructions presented on screen for use with
    a third-party Tester (such as the Bluetooth PTS).

BUG=chromium:256771
TEST=run_remote_tests

Change-Id: I851a05acff3ca3edba32bb2f0cd043d8042d162d
Reviewed-on: https://gerrit.chromium.org/gerrit/65074
Commit-Queue: Scott James Remnant <keybuk@chromium.org>
Reviewed-by: Scott James Remnant <keybuk@chromium.org>
Tested-by: Scott James Remnant <keybuk@chromium.org>
diff --git a/server/cros/bluetooth/bluetooth_client.py b/server/cros/bluetooth/bluetooth_client.py
index 063f624..46f27eb 100644
--- a/server/cros/bluetooth/bluetooth_client.py
+++ b/server/cros/bluetooth/bluetooth_client.py
@@ -120,6 +120,8 @@
 
     def close(self):
         """Tear down state associated with the client."""
+        # Turn off the discoverable flag since it may affect future tests.
+        self._proxy.set_discoverable(False)
         # Leave the adapter powered off, but don't do a full reset.
         self._proxy.set_powered(False)
         # This kills the RPC server.