Repaint SVG subtree on viewport changes (resize)

third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp

Index: third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
diff --git a/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp b/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
index 0334e0451cb9a8dda061ed26e77323ed82dd79f3..1d6b33d7073a642a4917d97739335c65e6776b19 100644
--- a/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp
@@ -153,17 +153,22 @@ void LayoutSVGRoot::layout() {
 
   SVGLayoutSupport::layoutResourcesIfNeeded(this);
 
+  // selfNeedsLayout() will cover changes to one (or more) of viewBox,
+  // current{Scale,Translate} and decorations.
+  const bool viewportMayHaveChanged = selfNeedsLayout() || oldSize != size();
+
+  // The scale of one or more of the SVG elements may have changed, or new
+  // content may have been exposed, so mark the entire subtree as needing paint
+  // invalidation checking. (It is only somewhat by coincidence that this
+  // condition happens to be the same as the one for viewport changes.)
+  if (viewportMayHaveChanged)
+    setMayNeedPaintInvalidationSubtree();
+
   SVGSVGElement* svg = toSVGSVGElement(node());
   ASSERT(svg);
   // When hasRelativeLengths() is false, no descendants have relative lengths
   // (hence no one is interested in viewport size changes).
-  m_isLayoutSizeChanged =
-      svg->hasRelativeLengths() && (selfNeedsLayout() || oldSize != size());
-
-  // The scale of one or more of the SVG elements may have changed, so mark
-  // the entire subtree as needing paint invalidation checking.
-  if (m_isLayoutSizeChanged)
-    setMayNeedPaintInvalidationSubtree();
+  m_isLayoutSizeChanged = viewportMayHaveChanged && svg->hasRelativeLengths();
 
   SVGLayoutSupport::layoutChildren(
       firstChild(), false, m_didScreenScaleFactorChange, m_isLayoutSizeChanged);