Merge "Add IBiometricsFace#userActivity"

     * Authenticates the active user.

     *

     * An optional operationId can be specified as a token from the transaction

     * being authorized.

     * being authorized. The hardware may enter a standby state during

     * authentication, where the device is idle to conserve power while

     * authenticating, e.g. after 3 seconds without finding a face. See

     * IBiometricsFace#userActivity() for more info.

     *

     * @param operationId A non-zero operation id associated with a crypto

     * object instance; or 0 if not being used.

     */

    @callflow(next={"cancel", "generateChallenge", "remove"})

    authenticate(uint64_t operationId) generates (Status status);

    /**

     * A hint to the HAL to continue looking for faces.

     *

     * This method should only be used when the HAL is in the authenticating

     * or standby state. Using this method when the HAL is not in one of the

     * mentioned states must return OPERATION_NOT_SUPPORTED. Calling this

     * method while the HAL is already authenticating may extend the duration

     * where it's looking for a face.

     *

     * @return status The status of this method call.

     */

    userActivity() generates (Status status);

};