* 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/browser.h
class Browser : public WindowListObserver {
 public:
  Browser();
  ~Browser() override;
  static Browser* Get();
  
  void Quit();
  
  void Exit(mate::Arguments* args);
  
  void Shutdown();
  
  void Focus();
  
  std::string GetVersion() const;
  
  void SetVersion(const std::string& version);
  
  std::string GetName() const;
  
  void SetName(const std::string& name);
  
  void AddRecentDocument(const base::FilePath& path);
  
  void ClearRecentDocuments();
  
  void SetAppUserModelID(const base::string16& name);