Slop region check for multi-finger scroll

ui/events/gesture_detection/gesture_listeners.h

Index: ui/events/gesture_detection/gesture_listeners.h
diff --git a/ui/events/gesture_detection/gesture_listeners.h b/ui/events/gesture_detection/gesture_listeners.h
index 6decce661335bd7959b8483650af58a81466025b..df2321e20996119b3fe800af82237b87546d7013 100644
--- a/ui/events/gesture_detection/gesture_listeners.h
+++ b/ui/events/gesture_detection/gesture_listeners.h
@@ -21,6 +21,7 @@ class GESTURE_DETECTION_EXPORT GestureListener {
   virtual void OnLongPress(const MotionEvent& e) = 0;
   virtual bool OnScroll(const MotionEvent& e1,
                         const MotionEvent& e2,
+                        const MotionEvent& secondary_pointer_down,
                         float distance_x,
                         float distance_y) = 0;
   virtual bool OnFling(const MotionEvent& e1,
@@ -59,6 +60,7 @@ class GESTURE_DETECTION_EXPORT SimpleGestureListener
   void OnLongPress(const MotionEvent& e) override;
   bool OnScroll(const MotionEvent& e1,
                 const MotionEvent& e2,
+                const MotionEvent& secondary_pointer_down,
                 float distance_x,
                 float distance_y) override;
   bool OnFling(const MotionEvent& e1,