The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/060a711d10ffa6eadb1e46e5b200b6ffb2dc83ef

commit 060a711d10ffa6eadb1e46e5b200b6ffb2dc83ef
Author: Joseph Hwang <josephsih@chromium.org>
Date: Fri Jan 13 07:16:29 2017

bluetooth_device_xmlrpc_server: catch dbus error properly.

In _find_device(), when executing dbus.Interface(), it may
return False if exceptions occur owing to the decorator,
@xmlrpc_server.dbus_safe(False).

In this patch, we would like to catch the error and display
the error log properly. For instance, if BlueZ crashes on
dereferencing a null pointer, the test server should capture
D-Bus interface exception. Refer to TEST below for catching
such a crash example through bluetooth autotests.

BUG= chromium:680913 
TEST=Perform the following steps:

(1) Reset bluez to the following commit.
    commit d9d6e06ce937f8c2e82898ff1442109539bea486
           CHROMIUM: supports a new dbus method ResetAdvertising
    Emerge and deploy bluez to a chromebook machine.
    For more information about the crash issue, refer to
    crbug.com/662144: Bluetooth is broken in Chrome OS.

    Please also refer to the following patch about what were fixed
    about the crash caused by scan.
    https://chromium.googlesource.com/chromiumos/third_party/bluez/+/4c86ad3816e5f1e62cbca09b232157f768afedd8%5E%21/
    Basically, that patch fixed the device flags type and size in
    /src/device.c in bluez.

(2) Run bluetooth_AdapterPairing autotest.
    (cr) $ test_that --args "chameleon_host=$CHAMELEON_IP" $CHROMEBOOK_IP
           bluetooth_AdapterPairing.mouse

    When executing test_discover_device, observe an exception as follows:

    test_discover_device:
        <Fault 1: "<type 'exceptions.Exception'>:dbus.Interface error">
    bluetoothd probably crash. Check out /var/log/messages.

(3) Remember to update your bluez back to the latest commit after testing.

Change-Id: I216adc626e0bf1dd7b02a416425693f8d14dde6b
Reviewed-on: https://chromium-review.googlesource.com/427425
Commit-Ready: Shyh-In Hwang <josephsih@chromium.org>
Tested-by: Shyh-In Hwang <josephsih@chromium.org>
Reviewed-by: Shyh-In Hwang <josephsih@chromium.org>

[modify] https://crrev.com/060a711d10ffa6eadb1e46e5b200b6ffb2dc83ef/server/cros/bluetooth/bluetooth_adpater_tests.py
[modify] https://crrev.com/060a711d10ffa6eadb1e46e5b200b6ffb2dc83ef/client/cros/bluetooth/bluetooth_device_xmlrpc_server.py