* 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
for (NativeWindowObserver& observer : observers_)
    observer.OnWindowBlur();
}
void NativeWindow::NotifyWindowFocus() {
  for (NativeWindowObserver& observer : observers_)
    observer.OnWindowFocus();
}
void NativeWindow::NotifyWindowShow() {
  for (NativeWindowObserver& observer : observers_)
    observer.OnWindowShow();
}
void NativeWindow::NotifyWindowHide() {
  for (NativeWindowObserver& observer : observers_)
    observer.OnWindowHide();
}
void NativeWindow::NotifyWindowMaximize() {
  for (NativeWindowObserver& observer : observers_)
    observer.OnWindowMaximize();
}
void NativeWindow::NotifyWindowUnmaximize() {
  for (NativeWindowObserver& observer : observers_)
    observer.OnWindowUnmaximize();
}
void NativeWindow::NotifyWindowMinimize() {