Simplified BluetoothDeviceMac.

BluetoothDeviceMac holds IOBluetoothDevice, an instance to a single remote Bluetooth device in OSX. BluetoothDeviceMac will use IOBluetoothDevice instance to run all the device-related functions instead of using cached data.

Also fixed rfcomm_channel bug in BluetoothSocketMac.

BUG=229636

Review URL: https://chromiumcodereview.appspot.com/13983004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@194020 0039d316-1c4b-4281-b951-d872f2087c98