- 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.cc
#include "base/json/json_writer.h"
#include "base/message_loop/message_loop.h"
#include "base/strings/utf_string_conversions.h"
#include "brightray/browser/inspectable_web_contents.h"
#include "brightray/browser/inspectable_web_contents_view.h"
#include "components/prefs/pref_service.h"
#include "content/browser/renderer_host/render_widget_host_impl.h"
#include "content/public/browser/navigation_entry.h"
#include "content/public/browser/plugin_service.h"
#include "content/public/browser/render_process_host.h"
#include "content/public/browser/render_view_host.h"
#include "content/public/browser/render_widget_host.h"
#include "content/public/browser/render_widget_host_view.h"
#include "content/public/common/content_switches.h"
#include "ipc/ipc_message_macros.h"
#include "native_mate/dictionary.h"
#include "third_party/skia/include/core/SkRegion.h"
#include "ui/gfx/codec/png_codec.h"
#include "ui/gfx/geometry/point.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gfx/geometry/size_conversions.h"
#include "ui/gl/gpu_switching_manager.h"
#if defined(OS_LINUX) || defined(OS_WIN)
#include "content/public/common/renderer_preferences.h"
#include "ui/gfx/font_render_params.h"
#endif
DEFINE_WEB_CONTENTS_USER_DATA_KEY(atom::NativeWindowRelay);
namespace atom {
NativeWindow::NativeWindow(