Optimize scroll adjustment for paint invalidation

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PaintInvalidator_h
 #define PaintInvalidator_h
 
 #include "platform/geometry/LayoutRect.h"
 #include "platform/graphics/paint/GeometryMapper.h"
 #include "wtf/Vector.h"
@@ skipping 12 matching lines @@
       : treeBuilderContext(treeBuilderContext), parentContext(nullptr) {}
 
   PaintInvalidatorContext(
       const PaintPropertyTreeBuilderContext& treeBuilderContext,
       const PaintInvalidatorContext& parentContext)
       : treeBuilderContext(treeBuilderContext),
         parentContext(&parentContext),
         forcedSubtreeInvalidationFlags(
             parentContext.forcedSubtreeInvalidationFlags),
         paintInvalidationContainer(parentContext.paintInvalidationContainer),
+        scrollAdjustment(parentContext.scrollAdjustment),
         paintInvalidationContainerForStackedContents(
             parentContext.paintInvalidationContainerForStackedContents),
         paintingLayer(parentContext.paintingLayer) {}
 
   // This method is temporary to adapt PaintInvalidatorContext and the legacy
   // PaintInvalidationState for code shared by old code and new code.
   virtual void mapLocalRectToVisualRectInBacking(const LayoutObject&,
                                                  LayoutRect&) const;
 
   const PaintPropertyTreeBuilderContext& treeBuilderContext;
@@ skipping 11 matching lines @@
   };
   unsigned forcedSubtreeInvalidationFlags = 0;
 
   // The following fields can be null only before
   // PaintInvalidator::updateContext().
 
   // The current paint invalidation container for normal flow objects.
   // It is the enclosing composited object.
   const LayoutBoxModelObject* paintInvalidationContainer = nullptr;
 
+  // Adjusts scrolling contents coordinates in non-composited paint invalidation
+  // container into container coordinates. It's empty for non-scrolling or
+  // composited-scrolling paint invalidation container.
+  IntSize scrollAdjustment;
+
   // The current paint invalidation container for stacked contents (stacking
   // contexts or positioned objects).  It is the nearest ancestor composited
   // object which establishes a stacking context.  See
   // Source/core/paint/README.md ### PaintInvalidationState for details on how
   // stacked contents' paint invalidation containers differ.
   const LayoutBoxModelObject* paintInvalidationContainerForStackedContents =
       nullptr;
 
   PaintLayer* paintingLayer = nullptr;
 
@@ skipping 37 matching lines @@
   ALWAYS_INLINE void updateVisualRect(const LayoutObject&,
                                       PaintInvalidatorContext&);
 
   Vector<const LayoutObject*> m_pendingDelayedPaintInvalidations;
   GeometryMapper& m_geometryMapper;
 };
 
 }  // namespace blink
 
 #endif  // PaintInvalidator_h