Log battery discharge during scenario.

[OlivierLi]

There should be a small standalone program that can be run next to the browser and logs the battery discharge.

This allows calculating how long the full battery would last if executing the scenario over and over.

If we only care about Chrome we could find a way to leverage the devtools protocol to query Power.Mac.BatteryDischarge.

If we want to compare to Safari it would be best to write a quick objc/swift program to do it. Optimally it would use something like Grand Central Dispatch to setup the sample collection to minimize the impact on the system.

[OlivierLi]

Completed.