* Electron version: 1.6.10
* Operating system: macOS Sierra 10.12.4 (16E195)

# Improve Handoff API support

Hi!

Today the API of Handoff provides the methods: `setUserActivity`, `getCurrentActivityType` and dispatch the event `continue-activity`

I'm using Handoff and noticed that in some circumstances the broadcast takes a long time to update its userInfo which does not happen on the native iOS client

1. To invalidate or resign the current activity we currently need to create a non-existing activity type and set it as the current activity. There's no way to handle the activity life cycle through electron.
2. When we need to update a given user activity userInfo frequently (i.e in response to a search bar's text changes), we have no efficient way. Setting a new userActivity with the updated information takes several seconds to bridge, whereas doing this on iOS native app is instantaneous.

I believe that exposing a bit more of the NSUserActivity API to Electron would help, namely `becomeCurrent`, `resignCurrent` and `invalidate` which would address point 1, and `needsSave` and a new event to allow updating an activity when needed to address point 2.
These are described in more detail in https://developer.apple.com/reference/foundation/nsuseractivity.

I'm are open to help in any way i can such as explaining how the native API work, providing sample code or testing possible implementations

Thank you!
atom/browser/api/atom_api_app.cc
bool override_argv = false;
  base::FilePath exec_path;
  relauncher::StringVector args;
  mate::Dictionary options;
  if (js_args->GetNext(&options)) {
    if (options.Get("execPath", &exec_path) | options.Get("args", &args))
      override_argv = true;
  }
  if (!override_argv) {
    const relauncher::StringVector& argv = atom::AtomCommandLine::argv();
    return relauncher::RelaunchApp(argv);
  }
  relauncher::StringVector argv;
  argv.reserve(1 + args.size());
  if (exec_path.empty()) {
    base::FilePath current_exe_path;
    base::PathService::Get(base::FILE_EXE, &current_exe_path);
    argv.push_back(current_exe_path.value());
  } else {
    argv.push_back(exec_path.value());
  }
  argv.insert(argv.end(), args.begin(), args.end());
  return relauncher::RelaunchApp(argv);
}
void App::DisableHardwareAcceleration(mate::Arguments* args) {