* 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
return g_browser_process->net_log();
}
content::BrowserMainParts* AtomBrowserClient::CreateBrowserMainParts(
    const content::MainFunctionParams& params) {
  return new AtomBrowserMainParts(params);
}
void AtomBrowserClient::WebNotificationAllowed(
    int render_process_id,
    const base::Callback<void(bool, bool)>& callback) {
  content::WebContents* web_contents =
      WebContentsPreferences::GetWebContentsFromProcessID(render_process_id);
  if (!web_contents) {
    callback.Run(false, false);
    return;
  }
  auto* permission_helper =
      WebContentsPermissionHelper::FromWebContents(web_contents);
  if (!permission_helper) {
    callback.Run(false, false);
    return;
  }
  permission_helper->RequestWebNotificationPermission(
      base::Bind(callback, web_contents->IsAudioMuted()));
}
void AtomBrowserClient::RenderProcessHostDestroyed(