Track whether a scroll sequence has been partially prevented

ui/events/gesture_detection/touch_disposition_gesture_filter.h

Index: ui/events/gesture_detection/touch_disposition_gesture_filter.h
diff --git a/ui/events/gesture_detection/touch_disposition_gesture_filter.h b/ui/events/gesture_detection/touch_disposition_gesture_filter.h
index 290afaaf6a8d3eed60e4226b51823c8833371f19..5895a6b5e2b0297d9190447d5aef48a3b2f7a557 100644
--- a/ui/events/gesture_detection/touch_disposition_gesture_filter.h
+++ b/ui/events/gesture_detection/touch_disposition_gesture_filter.h
@@ -66,14 +66,18 @@ class GESTURE_DETECTION_EXPORT TouchDispositionGestureFilter {
     // Returns true iff the gesture should be dropped.
     bool Filter(EventType type);
 
+    // Whether an event of |type| has been filtered from the current sequence.
+    bool HasFilteredGestureType(EventType type) const;
+
    private:
     // True iff the sequence has had any touch down event consumed.
     bool start_touch_consumed_;
     // True iff the most recently ack'ed touch event was consumed.
     bool current_touch_consumed_;
-    // If the previous gesture of a given type was dropped instead of being
-    // dispatched, its type will occur in this set.
+    // Indicates whether the previous gesture of a given type was dropped.
     BitSet32 last_gesture_of_type_dropped_;
+    // Indicates whether *any* previous gesture of a given type was dropped.
+    BitSet32 any_gesture_of_type_dropped_;
   };
 
   void FilterAndSendPacket(const GestureEventDataPacket& packet);