[not for review - epic CL] Adding Elastic+Momentum+Layered scrolling to views::ScrollView

cc/input/input_handler.h

Index: cc/input/input_handler.h
diff --git a/cc/input/input_handler.h b/cc/input/input_handler.h
index 4bf52d52809086f5e8d6b1b399ac90b19a593734..c3929c277d216b11c8f14292e2d3dcd5f9f4f954 100644
--- a/cc/input/input_handler.h
+++ b/cc/input/input_handler.h
@@ -8,6 +8,7 @@
 #include <memory>
 
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "cc/base/cc_export.h"
 #include "cc/input/event_listener_properties.h"
@@ -199,7 +200,9 @@ class CC_EXPORT InputHandler {
   virtual std::unique_ptr<SwapPromiseMonitor>
   CreateLatencyInfoSwapPromiseMonitor(ui::LatencyInfo* latency) = 0;
 
-  virtual ScrollElasticityHelper* CreateScrollElasticityHelper() = 0;
+  virtual ScrollElasticityHelper* CreateRootScrollElasticityHelper() = 0;
+  virtual base::WeakPtr<ScrollElasticityHelper>
+  ScrollElasticityHelperForScrollingLayer() = 0;
 
   // Called by the single-threaded UI Compositor to get or set the scroll offset
   // on the impl side. Retruns false if |layer_id| isn't in the active tree.