* refactor: use ObserverList::Notify() in shell/browser/window_list.cc
* refactor: use ObserverList::Notify() in shell/browser/web_contents_zoom_controller.cc
* refactor: use ObserverList::Notify() in shell/browser/usb/usb_chooser_context.cc
* refactor: use ObserverList::Notify() in shell/browser/usb/electron_usb_delegate.cc
* refactor: use ObserverList::Notify() in shell/browser/ui/views/menu_delegate.cc
* refactor: use ObserverList::Notify() in shell/browser/ui/tray_icon.cc
* refactor: use ObserverList::Notify() in shell/browser/ui/electron_menu_model.cc
* refactor: use ObserverList::Notify() in shell/browser/serial/serial_chooser_context.cc
* refactor: use ObserverList::Notify() in shell/browser/native_window.cc
* refactor: use ObserverList::Notify() in shell/browser/serial/electron_serial_delegate.cc
* refactor: use ObserverList::Notify() in shell/browser/browser.cc
* refactor: use ObserverList::Notify() in shell/browser/api/electron_api_web_contents.cc
* refactor: use ObserverList::Notify() in shell/browser/hid/electron_hid_delegate.cc
* refactor: use ObserverList::Notify() in shell/browser/hid/hid_chooser_context.cc