IIRC this is mostly to generalize the onConnect call... There was a leaked knowledge of PerformanceLogger, or maybe enabling the DevTools domain events on behalf of PerformanceLogger, into the common WD code that has no business knowing about PerformanceLogger specifically. The knowledge and management of PerformanceLogger (and in the future ConsoleLogger) should be confined to the LogManager, and the PerformanceLogger must do the enable() call (just like in chromedriver), not expect someone else to do it.

Those who implement ConnectListener get notified about each new WebInspector instance and can do whatever they like with it, in particular the PerformanceLogger enables Page Network Timeline domain events. The other refactored place is RemoteIOSWebDriver was sending Page.enable on behalf of BaseWebInspector (which uses Page events in its onMessage()), while now it's the BaseWebInspector itself sending it -- IMHO cleaner.