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

/cc @electron/code-owners 
shell/browser/api/electron_api_app.cc
const std::string& error) {
  Emit("continue-activity-error", type, error);
}
void App::OnContinueUserActivity(bool* prevent_default,
                                 const std::string& type,
                                 const base::DictionaryValue& user_info) {
  if (Emit("continue-activity", type, user_info)) {
    *prevent_default = true;
  }
}
void App::OnUserActivityWasContinued(const std::string& type,
                                     const base::DictionaryValue& user_info) {
  Emit("activity-was-continued", type, user_info);
}
void App::OnUpdateUserActivityState(bool* prevent_default,
                                    const std::string& type,
                                    const base::DictionaryValue& user_info) {
  if (Emit("update-activity-state", type, user_info)) {
    *prevent_default = true;
  }
}
void App::OnNewWindowForTab() {
  Emit("new-window-for-tab");
}
#endif
bool App::CanCreateWindow(