Use float for scroll offset.

third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.cpp

Index: third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.cpp
diff --git a/third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.cpp b/third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.cpp
index e3518e8738b58e352b99a0b268ea11343d73fb1d..5f840a25ee5da7761d5ef38a9307bac20940deb5 100644
--- a/third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.cpp
+++ b/third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.cpp
@@ -446,9 +446,10 @@ bool ScrollingCoordinator::scrollableAreaScrollLayerDidChange(
   WebLayer* containerLayer = toWebLayer(scrollableArea->layerForContainer());
   if (webLayer) {
     webLayer->setScrollClipLayer(containerLayer);
-    DoublePoint scrollPosition(scrollableArea->scrollPositionDouble() +
-                               toDoubleSize(scrollableArea->scrollOrigin()));
-    webLayer->setScrollPositionDouble(scrollPosition);
+    ScrollOffset scrollOffset(
+        toScrollOffset(FloatPoint(scrollableArea->scrollOrigin()) +
+                       scrollableArea->scrollOffset()));
+    webLayer->setScrollOffset(scrollOffset);
 
     webLayer->setBounds(scrollableArea->contentsSize());
     bool canScrollX = scrollableArea->userInputScrollable(HorizontalScrollbar);