Add chrome.bluetooth and chrome.bluetoothLowEnergy for android

They are the only valid profiles Android support. `GATT` and `GATT_SERVER` does not make much difference for now (Implementation of android-21 pasted below). I think it might matter in future SDKs.

I would like to create a `isConnected(ScanResult result)` static method, and share it with `ChromeBluetoothLowEnergy`.

```
    public List<BluetoothDevice> getConnectedDevices(int profile) {
        if (DBG) Log.d(TAG,"getConnectedDevices");
        if (profile != BluetoothProfile.GATT && profile != BluetoothProfile.GATT_SERVER) {
            throw new IllegalArgumentException("Profile not supported: " + profile);
        }

        List<BluetoothDevice> connectedDevices = new ArrayList<BluetoothDevice>();

        try {
            IBluetoothManager managerService = mAdapter.getBluetoothManager();
            IBluetoothGatt iGatt = managerService.getBluetoothGatt();
            if (iGatt == null) return connectedDevices;

            connectedDevices = iGatt.getDevicesMatchingConnectionStates(
                new int[] { BluetoothProfile.STATE_CONNECTED });
        } catch (RemoteException e) {
            Log.e(TAG,"",e);
        }

        return connectedDevices;
    }
```