events: Change gesture-event handler in EventHandler to not return any values.

ui/views/controls/scrollbar/native_scroll_bar.cc

Index: ui/views/controls/scrollbar/native_scroll_bar.cc
diff --git a/ui/views/controls/scrollbar/native_scroll_bar.cc b/ui/views/controls/scrollbar/native_scroll_bar.cc
index 77c4387fae92e7ef3b89a2a0111e032f4b334a72..0848576816f73602c4c4042f3eabcd6119258ea0 100644
--- a/ui/views/controls/scrollbar/native_scroll_bar.cc
+++ b/ui/views/controls/scrollbar/native_scroll_bar.cc
@@ -78,10 +78,10 @@ bool NativeScrollBar::OnKeyPressed(const ui::KeyEvent& event) {
   return native_wrapper_->GetView()->OnKeyPressed(event);
 }
 
-ui::EventResult NativeScrollBar::OnGestureEvent(ui::GestureEvent* event) {
+void NativeScrollBar::OnGestureEvent(ui::GestureEvent* event) {
   if (!native_wrapper_)
-    return ui::ER_UNHANDLED;
-  return native_wrapper_->GetView()->OnGestureEvent(event);
+    return;
+  native_wrapper_->GetView()->OnGestureEvent(event);
 }
 
 bool NativeScrollBar::OnMouseWheel(const ui::MouseWheelEvent& event) {