Adding momentum/overscroll to views:: ScrollViews

ui/events/blink/input_scroll_elasticity_controller.h

Index: ui/events/blink/input_scroll_elasticity_controller.h
diff --git a/ui/events/blink/input_scroll_elasticity_controller.h b/ui/events/blink/input_scroll_elasticity_controller.h
index bbbc445a6d87ecaa11ca4b6cf32e6725d399b698..322c2590cb350d55807524fb2282b2e1072d3481 100644
--- a/ui/events/blink/input_scroll_elasticity_controller.h
+++ b/ui/events/blink/input_scroll_elasticity_controller.h
@@ -45,11 +45,20 @@ namespace ui {
 
 class InputScrollElasticityController {
  public:
-  explicit InputScrollElasticityController(cc::ScrollElasticityHelper* helper);
+  InputScrollElasticityController();
   virtual ~InputScrollElasticityController();
 
   base::WeakPtr<InputScrollElasticityController> GetWeakPtr();
 
+  void SetActiveHelper(const base::WeakPtr<cc::ScrollElasticityHelper>& helper);
+
+  void ObserveRealScrollBegin(bool enter_momentum, bool leave_momentum);
+  void ObserveScrollUpdate(const gfx::Vector2dF& event_delta,
+                           const gfx::Vector2dF& unused_scroll_delta,
+                           const base::TimeTicks& event_timestamp,
+                           bool has_momentum);
+  void ObserveRealScrollEnd(const base::TimeTicks& event_timestamp);
+
   // Update the overscroll state based a gesture event that has been processed.
   // Note that this assumes that all events are coming from a single input
   // device. If the user simultaneously uses multiple input devices, Cocoa may
@@ -106,7 +115,7 @@ class InputScrollElasticityController {
   bool CanScrollHorizontally() const;
   bool CanScrollVertically() const;
 
-  cc::ScrollElasticityHelper* helper_;
+  base::WeakPtr<cc::ScrollElasticityHelper> helper_;
   State state_;
 
   // If there is no overscroll, require a minimum overscroll delta before