Repaint on interest rect change

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h

Index: third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
index 9d7507a30ce37e5812d80c2e131e60ff78652943..14ef046a486b1c98984a82ff5fceb968f9e43003 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
@@ -154,8 +154,7 @@ public:
     void notifyFirstTextPaint() override;
     void notifyFirstImagePaint() override;
 
-    void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect& clip) const override;
-    void paintContentsIfNeeded(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase) const override;
+    void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect* clip) const override;
     bool isTrackingPaintInvalidations() const override;
 
 #if ENABLE(ASSERT)
@@ -214,6 +213,7 @@ public:
 
 private:
     static IntRect computeInterestRect(const GraphicsLayer*, LayoutObject* owningLayoutObject);
+    static bool interestRectChangedEnoughToRepaint(const IntRect& previousInterestRect, const IntRect& newInterestRect, const IntSize& layerSize);
 
     static const GraphicsLayerPaintInfo* containingSquashedLayer(const LayoutObject*,  const Vector<GraphicsLayerPaintInfo>& layers, unsigned maxSquashedLayerIndex);
 
@@ -316,6 +316,8 @@ private:
     // not appear earlier in the set of layers for this object.
     bool invalidateLayerIfNoPrecedingEntry(size_t);
 
+    void paintContentsInternal(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect& interestRect) const;
+
     PaintLayer& m_owningLayer;
 
     // The hierarchy of layers that is maintained by the CompositedLayerMapping looks like this:
@@ -439,6 +441,8 @@ private:
     unsigned m_backgroundLayerPaintsFixedRootBackground : 1;
     unsigned m_scrollingContentsAreEmpty : 1;
 
+    mutable IntRect m_previousPaintInterestRect;
+
     friend class CompositedLayerMappingTest;
 };