device/bluetooth: Implement BluetoothGattConnection on Chrome OS.

device/bluetooth: Implement BluetoothGattConnection on Chrome OS.

This patch adds BluetoothGattConnectionChromeOS and implements
BluetoothDeviceChromeOS::CreateGattConnection. At this point, creating
a connection simply calls org.bluez.Device1.Connect without pairing.
BluetoothGattConnectionChromeOS::Disconnect currently doesn't do anything,
at least until there is a system in bluetoothd for managing GATT connections
properly between Chrome and its profiles and plugins.

BUG=384620, 381305
TEST=device_unittests

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=278595

[keybuk, 2014-06-19 17:10:37]

lgtm

[armansito, 2014-06-19 17:14:32]

The CQ bit was checked by armansito@chromium.org

[commit-bot: I haz the power, 2014-06-19 17:16:38]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/armansito@chromium.org/333983003/1

[commit-bot: I haz the power, 2014-06-20 04:40:49]

Change committed as 278595