* 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
brightray::InspectableWebContents* inspectable_web_contents,
    const mate::Dictionary& options,
    NativeWindow* parent)
    : content::WebContentsObserver(inspectable_web_contents->GetWebContents()),
      has_frame_(true),
      transparent_(false),
      enable_larger_than_screen_(false),
      is_closed_(false),
      sheet_offset_x_(0.0),
      sheet_offset_y_(0.0),
      aspect_ratio_(0.0),
      parent_(parent),
      is_modal_(false),
      inspectable_web_contents_(inspectable_web_contents),
      weak_factory_(this) {
  options.Get(options::kFrame, &has_frame_);
  options.Get(options::kTransparent, &transparent_);
  options.Get(options::kEnableLargerThanScreen, &enable_larger_than_screen_);
  if (parent)
    options.Get("modal", &is_modal_);
#if defined(OS_LINUX) || defined(OS_WIN)
  auto* prefs = web_contents()->GetMutableRendererPrefs();