Fixed clip resize for document.rootScroller with inertTopControls

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp

Index: third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
index ebe400f573dabc4f76ab52aa00f487e94387c851..caffe2e57c7001dddbe85c638268fdfacd83ef8f 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
@@ -1235,6 +1235,15 @@ void CompositedLayerMapping::updateScrollingLayerGeometry(
   LayoutBox* layoutBox = toLayoutBox(layoutObject());
   IntRect overflowClipRect =
       pixelSnappedIntRect(layoutBox->overflowClipRect(LayoutPoint()));
+
+  if (m_owningLayer.isGlobalRootScroller()) {
+    overflowClipRect.setSize(
+        flooredIntSize(layoutBox->document()

[chrishtr, 2016/11/18 00:37:09]

Can a LayoutView ever have a non-integral size? I think not. If so, assert that
the flooring has
no effect?

[bokan, 2016/11/18 22:30:35]

I think you're right. I switched it to pixelSnappedIntRect for consistency and
added a DCHECK.

+                           .layoutView()
+                           ->overflowClipRect(LayoutPoint())
+                           .size()));
+  }
+
   FloatPoint scrollPosition =
       m_owningLayer.getScrollableArea()->scrollPosition();
   m_scrollingLayer->setPosition(FloatPoint(