### Preflight Checklist

- [X] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
- [X] I have searched the [issue tracker](https://www.github.com/electron/electron/issues) for a feature request that matches the one I want to file, without success.

### Problem Description

Hi,

My team is trying to support universal linking in our application. Currently, in order to receive a handoff event from the browser, the application needs to listen to `continue-activity` event which provides `type` and `userInfo`. As per the Apple documentation [here](https://developer.apple.com/library/archive/documentation/UserExperience/Conceptual/Handoff/AdoptingHandoff/AdoptingHandoff.html#//apple_ref/doc/uid/TP40014338-CH2-SW10), the browser sends the app an `NSUserActivity` object with an `activityType` value of `NSUserActivityTypeBrowsingWeb`. The `webpageURL` property contains the URL the user was visiting, while the `userInfo` dictionary is empty. 

To provide a smooth handoff our application needs to know the URL the user is navigating from. Therefore, it would be great if the `webpageURL` parameter is exposed in `continue-activity` event. 


### Proposed Solution

The `NSUserActivity` object contains the `webpageURL` property which is set during the handoff process. 
I don't have any experience with Objective C but I believe the `webpageURL` property on the `userActivity` object can be allowed to pass [here](https://github.com/electron/electron/blob/da2baabb96161ea08a15820451f9374d63b4d678/shell/browser/mac/electron_application_delegate.mm#L161) to make it accessible.
https://github.com/electron/electron/blob/da2baabb96161ea08a15820451f9374d63b4d678/shell/browser/mac/electron_application_delegate.mm#L161


### Alternatives Considered

-

### Additional Information

The application needs to know the URL from where the user is navigating to provide a customized handoff experience. 
shell/browser/api/electron_api_app.cc
#if defined(OS_MAC) || defined(OS_WIN)
      .SetMethod("showEmojiPanel",
                 base::BindRepeating(&Browser::ShowEmojiPanel, browser))
#endif
#if defined(OS_WIN)
      .SetMethod("setUserTasks",
                 base::BindRepeating(&Browser::SetUserTasks, browser))
      .SetMethod("getJumpListSettings", &App::GetJumpListSettings)
      .SetMethod("setJumpList", &App::SetJumpList)
#endif
#if defined(OS_LINUX)
      .SetMethod("isUnityRunning",
                 base::BindRepeating(&Browser::IsUnityRunning, browser))
#endif
      .SetProperty("isPackaged", &App::IsPackaged)
      .SetMethod("setAppPath", &App::SetAppPath)
      .SetMethod("getAppPath", &App::GetAppPath)
      .SetMethod("setPath", &App::SetPath)
      .SetMethod("getPath", &App::GetPath)
      .SetMethod("setAppLogsPath", &App::SetAppLogsPath)
      .SetMethod("setDesktopName", &App::SetDesktopName)
      .SetMethod("getLocale", &App::GetLocale)
      .SetMethod("getLocaleCountryCode", &App::GetLocaleCountryCode)
#if defined(USE_NSS_CERTS)
      .SetMethod("importCertificate", &App::ImportCertificate)
#endif
      .SetMethod("hasSingleInstanceLock", &App::HasSingleInstanceLock)
      .SetMethod("requestSingleInstanceLock", &App::RequestSingleInstanceLock)
      .SetMethod("releaseSingleInstanceLock", &App::ReleaseSingleInstanceLock)
      .SetMethod("relaunch", &App::Relaunch)