Profile managers use the new class |BluetoothProfileResultHandler|
to signal the result of initializing of cleaning up operations to
|BluetoothServiceBluedroid|. |BluetoothServiceBluedroid| proceeds
once all profile handlers have finished.
Future patches will build upon this patch to create completely
asynchronous profile managers.
BluetoothProfileManagerBase is a base class of Bluetooth profile managers.
It will be a generic interface declaring basic functions that all profile
managers should implement, such as Connect(), Disconnect() and IsConnected().
Currently there is only one callback function OnGetServiceChannel(), which
will be called after calling BluetoothService::GetServiceChannel().
