I guess you mean: how does this relate to Loader.prototype.locate()? 

The default implementation of Loader.prototype.locate(load) return load.name, not useful.

When overridden by LoaderHooks.locate() (normal procedure), Loader.prototype.locate(load) returns LoaderHooks.locate(load).  

Thus we need an implementation of LoaderHooks.locate() that is useful on the platforms we support.