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

cc/input/input_handler.h

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_INPUT_INPUT_HANDLER_H_
 #define CC_INPUT_INPUT_HANDLER_H_
 
 #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"
 #include "cc/input/main_thread_scrolling_reason.h"
 #include "cc/input/scroll_state.h"
 #include "cc/input/scrollbar.h"
 #include "cc/trees/swap_promise_monitor.h"
 
 namespace gfx {
 class Point;
@@ skipping 171 matching lines @@
   virtual bool DoTouchEventsBlockScrollAt(const gfx::Point& viewport_point) = 0;
 
   // Calling CreateLatencyInfoSwapPromiseMonitor() to get a scoped
   // LatencyInfoSwapPromiseMonitor. During the life time of the
   // LatencyInfoSwapPromiseMonitor, if SetNeedsRedraw() or SetNeedsRedrawRect()
   // is called on LayerTreeHostImpl, the original latency info will be turned
   // into a LatencyInfoSwapPromise.
   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.
   virtual bool GetScrollOffsetForLayer(int layer_id,
                                        gfx::ScrollOffset* offset) = 0;
   virtual bool ScrollLayerTo(int layer_id, const gfx::ScrollOffset& offset) = 0;
 
  protected:
   InputHandler() {}
   virtual ~InputHandler() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(InputHandler);
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_INPUT_HANDLER_H_