Plumb smooth scrolling in Chromium compositor

content/renderer/input/input_handler_proxy_client.h

Index: content/renderer/input/input_handler_proxy_client.h
diff --git a/content/renderer/input/input_handler_proxy_client.h b/content/renderer/input/input_handler_proxy_client.h
index 53b4bc94846de1a4c6097587e25105dffa9ab86d..e3554d9988b606c378c485927f6c9cae8fe5dd3a 100644
--- a/content/renderer/input/input_handler_proxy_client.h
+++ b/content/renderer/input/input_handler_proxy_client.h
@@ -34,6 +34,17 @@ class InputHandlerProxyClient {
       const blink::WebFloatPoint& velocity,
       const blink::WebSize& cumulative_scroll) = 0;
 
+  // Creates a new smooth scrolling curve instance for device |device_source|
+  // starting at (|start_x|, |start_y|), ending at (|start_x| + |dx|, |start_y|
+  // + |dy|)
+  virtual blink::WebGestureCurve* CreateSmoothScrollAnimationCurve(
+      blink::WebGestureDevice deviceSource,
+      float start_x,
+      float start_y,
+      float dx,
+      float dy,
+      long duration) = 0;
+
   virtual void DidOverscroll(const DidOverscrollParams& params) = 0;
 
   virtual void DidStopFlinging() = 0;