* Electron version: 1.6.0
* Operating system: MacOS 10.12.2

### Expected behavior

'scroll-touch-end' emits when trackpad scrolling ends.

### Actual behavior

The begin event emits, but not the end

### How to reproduce

Example repo: https://github.com/pfrazee/electron-bug-no-scroll-touch-end

atom/browser/native_window.cc
const std::vector<DraggableRegion>& regions) {
  
  if (has_frame_)
    return;
  draggable_region_ = DraggableRegionsToSkRegion(regions);
}
void NativeWindow::ScheduleUnresponsiveEvent(int ms) {
  if (!window_unresposive_closure_.IsCancelled())
    return;
  window_unresposive_closure_.Reset(
      base::Bind(&NativeWindow::NotifyWindowUnresponsive,
                 weak_factory_.GetWeakPtr()));
  base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
      FROM_HERE,
      window_unresposive_closure_.callback(),
      base::TimeDelta::FromMilliseconds(ms));
}
void NativeWindow::NotifyWindowUnresponsive() {
  window_unresposive_closure_.Cancel();
  if (!is_closed_ && !IsUnresponsiveEventSuppressed() && IsEnabled()) {
    for (NativeWindowObserver& observer : observers_)
      observer.OnRendererUnresponsive();
  }
}
void NativeWindow::NotifyReadyToShow() {
  for (NativeWindowObserver& observer : observers_)
    observer.OnReadyToShow();
}
}