Optimize scroll adjustment for paint invalidation

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

 // Copyright 2014 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 PaintInvalidationState_h
 #define PaintInvalidationState_h
 
 #include "core/CoreExport.h"
 #include "core/paint/PaintInvalidator.h"
 #include "platform/geometry/LayoutRect.h"
@@ skipping 130 matching lines @@
   bool m_cachedOffsetsEnabled;
   bool m_cachedOffsetsForAbsolutePositionEnabled;
 
   // The following two fields are never null. Declare them as pointers because
   // we need some logic to initialize them in the body of the constructor.
 
   // The current paint invalidation container for normal flow objects.
   // It is the enclosing composited object.
   const LayoutBoxModelObject* m_paintInvalidationContainer;
 
+  // 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 m_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* m_paintInvalidationContainerForStackedContents;
 
   const LayoutObject& m_containerForAbsolutePosition;
 
   // Transform from the initial viewport coordinate system of an outermost
@@ skipping 31 matching lines @@
   void mapLocalRectToVisualRectInBacking(const LayoutObject&,
                                          LayoutRect&) const override;
 
  private:
   const PaintInvalidationState& m_paintInvalidationState;
 };
 
 }  // namespace blink
 
 #endif  // PaintInvalidationState_h