gaTooltip can be enabled and disabled programmatically.

Added Functions enableTooltip and disableTooltip to ga.Map.
Added property enabled to ga.Tooltip.
Adden Functiond enable and disable to ga.Tooltip.
Please document each function individually.

Also, make sure to have the correct annotation. You need to have @api here to have the function available in compiled mode. See other public functions on how you can achieve this.