Setting Accurate ScrollResult from Blink for Elastic Scroll.

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index ff314be36cba567af9beb0eb5d1a0de4e4ca688f..499fe4cbf9d4d1bddd6a4e2e58d74ba1e61953fa 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -2215,6 +2215,12 @@ void RenderWidget::didOverscroll(
     const blink::WebFloatSize& accumulatedRootOverScroll,
     const blink::WebFloatPoint& position,
     const blink::WebFloatSize& velocity) {
+  if (compositor_deps_->IsElasticOverscrollEnabled()) {
+    latest_overscroll_delta_ =
+        gfx::Vector2dF(-unusedDelta.width, -unusedDelta.height);
+    return;
+  }
+
   DidOverscrollParams params;
   // TODO(jdduke): Consider bundling the overscroll with the input event ack to
   // save an IPC.
@@ -2299,8 +2305,9 @@ void RenderWidget::ObserveWheelEventAndResult(
     scroll_result.did_scroll = true;
   } else {
     scroll_result.did_overscroll_root = true;
-    scroll_result.unused_scroll_delta =
-        gfx::Vector2dF(-wheel_event.deltaX, -wheel_event.deltaY);
+    scroll_result.unused_scroll_delta = latest_overscroll_delta_;
+    latest_overscroll_delta_.set_x(0);
+    latest_overscroll_delta_.set_y(0);
   }
 
   RenderThreadImpl* render_thread = RenderThreadImpl::current();