Merge "Improve docs for ro.input.video_enabled" into qt-dev am: 3c9aec6d

 * The system property ro.input.video_enabled can be used to control whether

 * EventHub scans and opens V4L devices. As V4L does not support multiple

 * clients, EventHub effectively blocks access to these devices when it opens

 * them. This property enables other clients to read these devices for testing

 * and development.

 * them.

 *

 * Setting this to "false" would prevent any video devices from being discovered and

 * associated with input devices.

 *

 * This property can be used as follows:

 * 1. To turn off features that are dependent on video device presence.

 * 2. During testing and development, to allow other clients to read video devices

 * directly from /dev.

 */

static bool isV4lScanningEnabled() {

  return property_get_bool("ro.input.video_enabled", true /* default_value */);