It's going to be removed from Chromium, see https://crbug.com/812523.

/cc @electron/code-owners 
shell/browser/api/electron_api_app.cc
if (Emit("before-quit")) {
    *prevent_default = true;
  }
}
void App::OnWillQuit(bool* prevent_default) {
  if (Emit("will-quit")) {
    *prevent_default = true;
  }
}
void App::OnWindowAllClosed() {
  Emit("window-all-closed");
}
void App::OnQuit() {
  int exitCode = ElectronBrowserMainParts::Get()->GetExitCode();
  Emit("quit", exitCode);
  if (process_singleton_) {
    process_singleton_->Cleanup();
    process_singleton_.reset();
  }
}
void App::OnOpenFile(bool* prevent_default, const std::string& file_path) {
  if (Emit("open-file", file_path)) {
    *prevent_default = true;
  }
}
void App::OnOpenURL(const std::string& url) {
  Emit("open-url", url);
}
void App::OnActivate(bool has_visible_windows) {