* 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
Emit("accessibility-support-changed", IsAccessibilitySupportEnabled());
}
#if defined(OS_MACOSX)
void App::OnWillContinueUserActivity(bool* prevent_default,
                                     const std::string& type) {
  if (Emit("will-continue-activity", type)) {
    *prevent_default = true;
  }
}
void App::OnDidFailToContinueUserActivity(const std::string& type,
                                          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,