Don't invalidate paint on background image change if it's obscured

third_party/WebKit/Source/core/layout/LayoutObject.h

Index: third_party/WebKit/Source/core/layout/LayoutObject.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutObject.h b/third_party/WebKit/Source/core/layout/LayoutObject.h
index 24d2c5e56c6c9f33209c4cf415707a6e51b5b473..51f6b9e7ea538991aa86c025c6302662933ba1b9 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.h
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.h
@@ -1341,6 +1341,9 @@ public:
     bool mayNeedPaintInvalidationSubtree() const { return m_bitfields.mayNeedPaintInvalidationSubtree(); }
     void setMayNeedPaintInvalidationSubtree();
 
+    bool mayNeedPaintInvalidationAnimatedBackgroundImage() const { return m_bitfields.mayNeedPaintInvalidationAnimatedBackgroundImage(); }
+    void setMayNeedPaintInvalidationAnimatgedBackgroundImage();
+
     bool shouldInvalidateSelection() const { return m_bitfields.shouldInvalidateSelection(); }
     void setShouldInvalidateSelection();
 
@@ -1734,6 +1737,7 @@ private:
             , m_childShouldCheckForPaintInvalidation(false)
             , m_mayNeedPaintInvalidation(false)
             , m_mayNeedPaintInvalidationSubtree(false)
+            , m_mayNeedPaintInvalidationAnimatedBackgroundImage(false)
             , m_shouldInvalidateSelection(false)
             , m_floating(false)
             , m_isAnonymous(!node)
@@ -1769,7 +1773,7 @@ private:
         {
         }
 
-        // 32 bits have been used in the first word, and 17 in the second.
+        // 32 bits have been used in the first word, and 18 in the second.
 
         // Self needs layout means that this layout object is marked for a full layout.
         // This is the default layout but it is expensive as it recomputes everything.
@@ -1820,6 +1824,7 @@ private:
         ADD_BOOLEAN_BITFIELD(childShouldCheckForPaintInvalidation, ChildShouldCheckForPaintInvalidation);
         ADD_BOOLEAN_BITFIELD(mayNeedPaintInvalidation, MayNeedPaintInvalidation);
         ADD_BOOLEAN_BITFIELD(mayNeedPaintInvalidationSubtree, MayNeedPaintInvalidationSubtree);
+        ADD_BOOLEAN_BITFIELD(mayNeedPaintInvalidationAnimatedBackgroundImage, MayNeedPaintInvalidationAnimatedBackgroundImage);
         ADD_BOOLEAN_BITFIELD(shouldInvalidateSelection, ShouldInvalidateSelection);
 
         // This boolean is the cached value of 'float'