Menu item 'Module Browser' invokes '<<open-class-browser>>', which calls Editor_Window.open_module_browser.  If the window is an actual editor, its path is used; otherwise open_module is called.  In either case, ModuleBrowser is called with flist and path pieces.

PathBrowser subclasses ModuleBrowser.  Menu item 'Path Browser' invokes '<<open-path-browser>>', which calls Editor_Window.open_path_browser, which calles PathBrowser.  PathBrowser.__init__'s only parameter is flist and it does not call ModuleBrowser.__init__.  So the APIs are independent and can be modified or not separately.  

For ModuleBrowser, changing flist to master and changing (name, path) to to filepath can be done independently.