* Output of `node_modules/.bin/electron --version`: v5.0.0-nightly.20190107
* Operating System (Platform and Version): macOS Mojave 10.14.2 (18C54)
* Output of `node_modules/.bin/electron --version` on last known working Electron version (if applicable): never

**Expected Behavior**
Using navigator.mediaDevices.getDisplayMedia({ video: true }), a native screen picker should appear.

**Actual behavior**
The following error is thrown: NotAllowedError: Permission denied

**Screenshots**
Expected dialog
![image](https://user-images.githubusercontent.com/1120050/51625551-71736500-1f0b-11e9-9a95-1406cad95046.png)
atom/browser/atom_browser_client.cc
content::WebPreferences* prefs) {
  prefs->javascript_enabled = true;
  prefs->web_security_enabled = true;
  prefs->plugins_enabled = true;
  prefs->dom_paste_enabled = true;
  prefs->allow_scripts_to_close_windows = true;
  prefs->javascript_can_access_clipboard = true;
  prefs->local_storage_enabled = true;
  prefs->databases_enabled = true;
  prefs->application_cache_enabled = true;
  prefs->allow_universal_access_from_file_urls = true;
  prefs->allow_file_access_from_file_urls = true;
  prefs->webgl1_enabled = true;
  prefs->webgl2_enabled = true;
  prefs->allow_running_insecure_content = false;
  prefs->default_minimum_page_scale_factor = 1.f;
  prefs->default_maximum_page_scale_factor = 1.f;
  prefs->navigate_on_drag_drop = false;
  SetFontDefaults(prefs);
  
  auto* web_contents = content::WebContents::FromRenderViewHost(host);
  auto* web_preferences = WebContentsPreferences::From(web_contents);
  if (web_preferences)
    web_preferences->OverrideWebkitPrefs(prefs);
}
content::ContentBrowserClient::SiteInstanceForNavigationType