* 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
int x = -1, y = -1;
  bool center;
  if (options.Get(options::kX, &x) && options.Get(options::kY, &y)) {
    SetPosition(gfx::Point(x, y));
  } else if (options.Get(options::kCenter, &center) && center) {
    Center();
  }
  
  extensions::SizeConstraints size_constraints(GetContentSizeConstraints());
  int min_height = 0, min_width = 0;
  if (options.Get(options::kMinHeight, &min_height) |
      options.Get(options::kMinWidth, &min_width)) {
    size_constraints.set_minimum_size(gfx::Size(min_width, min_height));
  }
  int max_height = INT_MAX, max_width = INT_MAX;
  if (options.Get(options::kMaxHeight, &max_height) |
      options.Get(options::kMaxWidth, &max_width)) {
    size_constraints.set_maximum_size(gfx::Size(max_width, max_height));
  }
  bool use_content_size = false;
  options.Get(options::kUseContentSize, &use_content_size);
  if (use_content_size) {
    SetContentSizeConstraints(size_constraints);
  } else {
    SetSizeConstraints(size_constraints);
  }
#if defined(USE_X11)
  bool resizable;
  if (options.Get(options::kResizable, &resizable)) {