The helper functions for slop region check and subtraction are modified.

ui/events/gesture_detection/gesture_detector.h

Index: ui/events/gesture_detection/gesture_detector.h
diff --git a/ui/events/gesture_detection/gesture_detector.h b/ui/events/gesture_detection/gesture_detector.h
index df5e6d5ec773a9b0b304ca139936c73cba7f99c6..148d4590df219355daf905a3b1adbfdab4b4dc0b 100644
--- a/ui/events/gesture_detection/gesture_detector.h
+++ b/ui/events/gesture_detection/gesture_detector.h
@@ -99,6 +99,15 @@ class GESTURE_DETECTION_EXPORT GestureDetector {
   void set_longpress_enabled(bool enabled) { longpress_enabled_ = enabled; }
   void set_showpress_enabled(bool enabled) { showpress_enabled_ = enabled; }
 
+  // Returns the event storing the initial position of the pointer with given
+  // pointer ID. The source could be either the current_down_event_ or
+  // secondary_pointer_down_event_.

[tdresser, 2016/07/22 19:51:28]

State that this returns nullptr if the source event isn't current or secondary.

[sahel, 2016/07/25 15:16:33]

Done.

+  const MotionEvent* GetSourcePointerDownEvent(
+      const MotionEvent& current_down_event,
+      const MotionEvent& secondary_pointer_down_event,
+      const int pointer_id);
+  int getPointerIndex(const MotionEvent& event, const int pointer_id);

[tdresser, 2016/07/22 19:51:28]

State that this returns -1 if it can't find it.

[sahel, 2016/07/25 15:16:33]

Done.

+
  private:
   void Init(const Config& config);
   void OnShowPressTimeout();