Remove unused Disconnect method in BluetoothHIDFlow

This method does not appear to be used, and has a name collision
with code in the RN42 class, which we do use.

Flip the method resolution order in BluetoothHIDMouseFlow,
so that if this conflict happens again, we'll be more likely
to catch it when editing the BluetoothHIDMouse hierarchy.

Added a note to help remind future readers that this functionality
exists in case it becomes relevant, as other flows seem to use it.

BUG=chromium:752719
TEST=Run this code on the Chameleon board:
$ make && make remote-install CHAMELEON_HOST=$CHAMELEON_IP
Execute the non-flaky non-stress tests that use this code,
and watch them pass:
$ test_that --board ${BOARD} --args "chameleon_host=${CHAMELEON_IP}" \
${DUT_IP} bluetooth_AdapterPairing.mouse \
bluetooth_AdapterPairing.mouse.pairing_twice \
bluetooth_AdapterHIDReports.mouse

Change-Id: Id417203ebbda06178466211bf95e8720479fe0b1
Reviewed-on: https://chromium-review.googlesource.com/609684
Commit-Ready: Alexander Lent <alent@google.com>
Tested-by: Alexander Lent <alent@google.com>
Reviewed-by: Wai-Hong Tam <waihong@google.com>
Reviewed-by: Miao-chen Chou <mcchou@chromium.org>
diff --git a/chameleond/devices/bluetooth_hid_flow.py b/chameleond/devices/bluetooth_hid_flow.py
index d09cf15..c9ecb3d 100644
--- a/chameleond/devices/bluetooth_hid_flow.py
+++ b/chameleond/devices/bluetooth_hid_flow.py
@@ -46,6 +46,11 @@
     # not get confused when trying to enumerate this USB device.
     self._usb_ctrl.EnableUSBOTGDriver()
     self._usb_ctrl.EnableDriver()
+    # Our Bluetooth HID flow differs substantially from other flows.
+    # We enable the driver in IsDetected (instead of in InitDevice),
+    # initialize a TTY, and report detecting it instead of a driver.
+    # (Other USB flows simulate Plug/Unplug by Enabling/Diabling the driver.)
+    # To Disable the driver, we could use use: self._usb_ctrl.DisableDriver()
     try:
       common.WaitForCondition(
           lambda: bool(serial_utils.FindTtyByDriver(self.SERIAL_DRIVER)),
@@ -100,10 +105,6 @@
     """
     logging.debug('Bluetooth HID flow #%d: Unplug() called.', self._port_id)
 
-  def Disconnect(self):
-    """Disconnect to the device by removing the serial driver."""
-    self._usb_ctrl.DisableDriver()
-
   def DoFSM(self):
     """fpga_tio calls DoFSM after a flow is selected.
 
@@ -112,7 +113,7 @@
     logging.debug('Bluetooth HID flow #%d: DoFSM() called.', self._port_id)
 
 
-class BluetoothHIDMouseFlow(BluetoothHIDMouse, BluetoothHIDFlow):
+class BluetoothHIDMouseFlow(BluetoothHIDFlow, BluetoothHIDMouse):
   """A flow object that emulates a classic bluetooth mouse device."""
 
   def __init__(self, port_id, usb_ctrl):