Safari Technology Preview now supports dark mode via `@media (prefers-color-scheme: dark)` in CSS media queries. 

Same should be supported in Electron apps to enable automatic light/dark mode switching.

shell/browser/atom_browser_client.cc
int process_id,
    AtomBrowserClient::ProcessPreferences prefs) {
  base::AutoLock auto_lock(process_preferences_lock_);
  process_preferences_[process_id] = prefs;
}
void AtomBrowserClient::RemoveProcessPreferences(int process_id) {
  base::AutoLock auto_lock(process_preferences_lock_);
  process_preferences_.erase(process_id);
}
bool AtomBrowserClient::IsProcessObserved(int process_id) const {
  base::AutoLock auto_lock(process_preferences_lock_);
  return process_preferences_.find(process_id) != process_preferences_.end();
}
bool AtomBrowserClient::IsRendererSandboxed(int process_id) const {