Revert of Remove obsolete code that invalidates document element on LayoutView resize (patchset #3 …

third_party/WebKit/Source/core/layout/LayoutView.cpp

Index: third_party/WebKit/Source/core/layout/LayoutView.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutView.cpp b/third_party/WebKit/Source/core/layout/LayoutView.cpp
index f211a982b81cdf218b5e0441a5a251c52b194d3a..6e5bbf09012e2e1d53e4a08f8e72c507e3c2b3f4 100644
--- a/third_party/WebKit/Source/core/layout/LayoutView.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutView.cpp
@@ -247,6 +247,8 @@ void LayoutView::layout() {
 
   SubtreeLayoutScope layoutScope(*this);
 
+  LayoutRect oldLayoutOverflowRect = layoutOverflowRect();
+
   // Use calcWidth/Height to get the new width/height, since this will take the
   // full page zoom factor into account.
   bool relayoutChildren =
@@ -281,6 +283,17 @@ void LayoutView::layout() {
 
   layoutContent();
 
+  if (layoutOverflowRect() != oldLayoutOverflowRect) {
+    // The document element paints the viewport background, so we need to
+    // invalidate it when layout overflow changes.
+    // FIXME: Improve viewport background styling/invalidation/painting.
+    // crbug.com/475115
+    if (Element* documentElement = document().documentElement()) {
+      if (LayoutObject* rootObject = documentElement->layoutObject())
+        rootObject->setShouldDoFullPaintInvalidation();
+    }
+  }
+
 #if ENABLE(ASSERT)
   checkLayoutState();
 #endif