private function _sync_clock_diff( $diff = false ) {
			$this->_logger->entrance();

			// Sync clock and store.
			$new_clock_diff = ( false === $diff ) ?
				Freemius_Api_WordPress::FindClockDiff() :
				$diff;

			if ( $new_clock_diff === self::$_clock_diff ) {
				return false;
			}

			self::$_clock_diff = $new_clock_diff;

			// Update API clock's diff.
			Freemius_Api_WordPress::SetClockDiff( self::$_clock_diff );

			// Store new clock diff in storage.
			self::$_options->set_option( 'api_clock_diff', self::$_clock_diff, true );

			return $new_clock_diff;
		}