* 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
base::AutoLock auto_lock(process_preferences_lock_);
  auto it = process_preferences_.find(process_id);
  return it != process_preferences_.end() && it->second.sandbox;
}
bool AtomBrowserClient::RendererUsesNativeWindowOpen(int process_id) const {
  base::AutoLock auto_lock(process_preferences_lock_);
  auto it = process_preferences_.find(process_id);
  return it != process_preferences_.end() && it->second.native_window_open;
}
bool AtomBrowserClient::RendererDisablesPopups(int process_id) const {
  base::AutoLock auto_lock(process_preferences_lock_);
  auto it = process_preferences_.find(process_id);
  return it != process_preferences_.end() && it->second.disable_popups;
}
std::string AtomBrowserClient::GetAffinityPreference(
    content::RenderFrameHost* rfh) const {
  auto* web_contents = content::WebContents::FromRenderFrameHost(rfh);
  auto* web_preferences = WebContentsPreferences::From(web_contents);
  std::string affinity;
  if (web_preferences &&
      web_preferences->GetPreference("affinity", &affinity) &&
      !affinity.empty()) {
    affinity = base::ToLowerASCII(affinity);
  }
  return affinity;
}
content::SiteInstance* AtomBrowserClient::GetSiteInstanceFromAffinity(