- Electron version: v1.3.3
- Operating system: OS X 10.11.6

v1.3.3 broke the detection of the `scroll-touch-begin` and `scroll-touch-end` events for me within a `webview`. It looks like the pull request #6754 caused this issue. v1.3.2 works as expected.

Behavior that I'm observing on v1.3.3:
- Most of the time, the `scroll-touch-*` events are not emitted when the cursor is on top of a `webview`.
- The `scroll-touch-*` events seem to be emitted _only once_ when the cursor is on a `webview` and on a scrollable element. The scrollable elements in my app have no native scrollbar set (they have the style `overflow: hidden;` set instead of `overflow: scroll;`). This is the case in which I need to receive the `scroll-touch-*` events.
- The `scroll-touch-*` events seem to work fine when the cursor is outside of the `webview` tag.

atom/browser/native_window.h
public content::WebContentsObserver {
 public:
  ~NativeWindow() override;
  
  
  static NativeWindow* Create(
      brightray::InspectableWebContents* inspectable_web_contents,
      const mate::Dictionary& options,
      NativeWindow* parent = nullptr);
  
  static NativeWindow* FromWebContents(content::WebContents* web_contents);
  void InitFromOptions(const mate::Dictionary& options);
  virtual void Close() = 0;
  virtual void CloseImmediately() = 0;
  virtual bool IsClosed() const { return is_closed_; }
  virtual void Focus(bool focus) = 0;
  virtual bool IsFocused() = 0;
  virtual void Show() = 0;
  virtual void ShowInactive() = 0;
  virtual void Hide() = 0;
  virtual bool IsVisible() = 0;
  virtual bool IsEnabled() = 0;
  virtual void Maximize() = 0;
  virtual void Unmaximize() = 0;
  virtual bool IsMaximized() = 0;
  virtual void Minimize() = 0;
  virtual void Restore() = 0;
  virtual bool IsMinimized() = 0;
  virtual void SetFullScreen(bool fullscreen) = 0;
  virtual bool IsFullscreen() const = 0;