Define contentsProperties on ObjectPaintProperties, for use in paint invalidation.

third_party/WebKit/Source/core/paint/ObjectPaintProperties.h

Index: third_party/WebKit/Source/core/paint/ObjectPaintProperties.h
diff --git a/third_party/WebKit/Source/core/paint/ObjectPaintProperties.h b/third_party/WebKit/Source/core/paint/ObjectPaintProperties.h
index 9c9a1a7ef390ce1af5aa1dff570c137d6ca4184e..3f22e76c7c2c2daa259e338fd6e9a71977a86ce4 100644
--- a/third_party/WebKit/Source/core/paint/ObjectPaintProperties.h
+++ b/third_party/WebKit/Source/core/paint/ObjectPaintProperties.h
@@ -77,6 +77,9 @@ public:
         PropertyTreeState propertyTreeState;
     };
     const LocalBorderBoxProperties* localBorderBoxProperties() const { return m_localBorderBoxProperties.get(); }
+    // ContentsProperties is the PropertyTreeState state that is the same as in localBorderBoxProperties, except that it is inside
+    // any clips and scrolls caused by this object. This PropertyTreeState is suitable as the destination for paint invalidation.
+    const PropertyTreeState* contentsProperties() const { return m_contentsProperties.get(); }
 
     void clearPaintOffsetTranslation() { m_paintOffsetTranslation = nullptr; }
     void clearTransform() { m_transform = nullptr; }
@@ -109,6 +112,7 @@ public:
     template <typename... Args> ClipPaintPropertyNode* createOrUpdateOverflowClip(Args&&... args) { return createOrUpdateProperty(m_overflowClip, std::forward<Args>(args)...); }
 
     void setLocalBorderBoxProperties(std::unique_ptr<LocalBorderBoxProperties> properties) { m_localBorderBoxProperties = std::move(properties); }
+    void setContentsProperties(std::unique_ptr<PropertyTreeState> properties) { m_contentsProperties = std::move(properties); }
 
 private:
     ObjectPaintProperties() { }
@@ -136,6 +140,7 @@ private:
     RefPtr<TransformPaintPropertyNode> m_scrollbarPaintOffset;
 
     std::unique_ptr<LocalBorderBoxProperties> m_localBorderBoxProperties;
+    std::unique_ptr<PropertyTreeState> m_contentsProperties;

[pdr., 2016/08/31 04:48:52]

Instead of caching such a large object, could we compute this dynamically in
O(1) using LocalBorderBoxProperties and the nodes on ObjectPaintProperties?

[szager1, 2016/08/31 16:31:22]

+1, I don't think it should be stored; it should be generated dynamically on
each call to contentsProperties().

[chrishtr, 2016/08/31 17:43:30]

Yes. I think you could say the same for localBorderBoxProperties. I can change
one or both. Why was it cached for the other one? Is it anticipated to be used
often?

 };
 
 } // namespace blink