Refactor to support default Bluetooth pairing delegate

In order to support a default pairing delegate we need to move the agent
service provider delegate implementation from BluetoothDevice to
BluetoothAdapter while retaining the existing API.

BUG=338492
TEST=device_unittests, unit_tests, browser_tests

Review URL: https://codereview.chromium.org/148293003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252216 0039d316-1c4b-4281-b951-d872f2087c98
uint32 BluetoothDeviceChromeOS::GetBluetoothClass() const {
  BluetoothDeviceClient::Properties* properties =
      DBusThreadManager::Get()->GetBluetoothDeviceClient()->
          GetProperties(object_path_);
  DCHECK(properties);

  return properties->bluetooth_class.value();
}

uint32 BluetoothDeviceChromeOS::GetBluetoothClass() const {
  BluetoothDeviceClient::Properties* properties =
      DBusThreadManager::Get()->GetBluetoothDeviceClient()->
          GetProperties(object_path_);
  DCHECK(properties);

  return properties->bluetooth_class.value();
}
