Revert 124071 - Gestures are now possible using touch events with any ids

ui/aura/gestures/gesture_point.h

Index: ui/aura/gestures/gesture_point.h
===================================================================
--- ui/aura/gestures/gesture_point.h	(revision 124450)
+++ ui/aura/gestures/gesture_point.h	(working copy)
@@ -53,17 +53,9 @@
   double last_touch_time() const { return last_touch_time_; }
   const gfx::Point& last_touch_position() const { return last_touch_position_; }
 
-  // point_id_ is used to drive GestureSequence::ProcessTouchEventForGesture.
-  // point_ids are maintained such that the set of point_ids is always
-  // contiguous, from 0 to the number of current touches.
-  // A lower point_id indicates that a touch occurred first.
-  // A negative point_id indicates that the GesturePoint is not currently
-  // associated with a touch.
-  void set_point_id(int point_id) { point_id_ = point_id; }
-  const int point_id() const { return point_id_; }
+  void set_touch_id(unsigned int touch_id) { touch_id_ = touch_id; }
+  unsigned int touch_id() const { return touch_id_; }
 
-  const bool in_use() const { return point_id_ >= 0; }
-
   double x_delta() const {
     return last_touch_position_.x() - first_touch_position_.x();
   }
@@ -95,7 +87,7 @@
 
   VelocityCalculator velocity_calculator_;
 
-  int point_id_;
+  unsigned int touch_id_;
   DISALLOW_COPY_AND_ASSIGN(GesturePoint);
 };