BSF_Analytics::maybe_migrate_options()

		private function maybe_migrate_options() {
			if ( get_site_option( 'bsf_usage_migrated' ) ) {
				return;
			}

			// Migrate global options.
			$old_last_displayed = get_site_option( 'bsf_analytics_last_displayed_time' );
			if ( false !== $old_last_displayed ) {
				update_site_option( 'bsf_usage_last_displayed_time', $old_last_displayed );
				delete_site_option( 'bsf_analytics_last_displayed_time' );
			}

			// Migrate per-product options.
			foreach ( $this->entities as $key => $data ) {
				$old_optin = get_site_option( $key . '_analytics_optin' );
				if ( false !== $old_optin ) {
					update_site_option( $key . '_usage_optin', $old_optin );
					delete_site_option( $key . '_analytics_optin' );
				}

				$old_install_time = get_site_option( $key . '_analytics_installed_time' );
				if ( false !== $old_install_time ) {
					update_site_option( $key . '_usage_installed_time', $old_install_time );
					delete_site_option( $key . '_analytics_installed_time' );
				}
			}

			// Migrate transient.
			$old_track = get_site_transient( 'bsf_analytics_track' );
			if ( false !== $old_track ) {
				set_site_transient( 'bsf_usage_track', $old_track, 2 * DAY_IN_SECONDS );
				delete_site_transient( 'bsf_analytics_track' );
			}

			update_site_option( 'bsf_usage_migrated', true );
		}