Update PaintLayer size during layout, not after.

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 288b0a55a2924a03b036725e52a5658020feb0bf..509a6aa7d1083ea8bd13a2acdf78943263543d3e 100644
--- a/third_party/WebKit/Source/core/layout/LayoutView.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutView.cpp
@@ -37,6 +37,7 @@
 #include "core/layout/api/LayoutPartItem.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/layout/compositing/PaintLayerCompositor.h"
+#include "core/page/ChromeClient.h"
 #include "core/page/Page.h"
 #include "core/paint/PaintLayer.h"
 #include "core/paint/ViewPaintInvalidator.h"
@@ -278,6 +279,25 @@ void LayoutView::UpdateLayout() {
       !ShouldUsePrintingLayout() &&
       (!frame_view_ || LogicalWidth() != ViewLogicalWidthForBoxSizing() ||
        LogicalHeight() != ViewLogicalHeightForBoxSizing());
+
+  if (!relayout_children && GetDocument().IsSVGDocument()) {
+    for (LayoutObject* child = FirstChild(); child;
+         child = child->NextSibling()) {
+      if (!child->IsSVGRoot())
+        continue;
+      const Length& child_height = child->Style()->LogicalHeight();
+      if (!child_height.IsPercentOrCalc())
+        continue;
+      if (ToLayoutBox(child)->LogicalHeight() !=
+          ValueForLength(child_height,
+                         AvailableLogicalHeightUsing(
+                             child_height, kExcludeMarginBorderPadding))) {
+        relayout_children = true;
+        layout_scope.SetChildNeedsLayout(child);
+      }
+    }
+  }
+
   if (relayout_children) {
     layout_scope.SetChildNeedsLayout(this);
     for (LayoutObject* child = FirstChild(); child;
@@ -701,6 +721,22 @@ float LayoutView::ZoomFactor() const {
   return frame_view_->GetFrame().PageZoomFactor();
 }
 
+void LayoutView::UpdateAfterLayout() {
+  // Unlike every other layer, the root PaintLayer takes its size from the
+  // layout viewport size.  The call to AdjustViewSize() will update the
+  // frame's contents size, which will also update the page's minimum scale
+  // factor.  The call to ResizeAfterLayout() will calculate the layout viewport
+  // size based on the page minimum scale factor, and then update the FrameView
+  // with the new size.
+  if (HasOverflowClip())
+    GetScrollableArea()->ClampScrollOffsetAfterOverflowChange();
+  LocalFrame& frame = GetFrameView()->GetFrame();
+  if (!GetDocument().Printing())
+    GetFrameView()->AdjustViewSize();
+  frame.GetChromeClient().ResizeAfterLayout(&frame);
+  LayoutBlock::UpdateAfterLayout();
+}
+
 void LayoutView::UpdateHitTestResult(HitTestResult& result,
                                      const LayoutPoint& point) {
   if (result.InnerNode())