Store previous painting clip rects on FragmentData.

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

 // Copyright 2015 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 PrePaintTreeWalk_h
 #define PrePaintTreeWalk_h
 
 #include "core/paint/ClipRect.h"
 #include "core/paint/PaintInvalidator.h"
 #include "core/paint/PaintPropertyTreeBuilder.h"
 
 namespace blink {
 
 class FrameView;
 class LayoutObject;
 class PropertyTreeState;
 struct PrePaintTreeWalkContext;
 
 // This class walks the whole layout tree, beginning from the root FrameView,
 // across frame boundaries. Helper classes are called for each tree node to
 // perform actual actions.  It expects to be invoked in InPrePaint phase.
-class PrePaintTreeWalk {
+class CORE_EXPORT PrePaintTreeWalk {
  public:
   PrePaintTreeWalk() {}
   void Walk(FrameView& root_frame);
 
  private:
   void Walk(FrameView&, const PrePaintTreeWalkContext&);
   void Walk(const LayoutObject&, const PrePaintTreeWalkContext&);
 
   // Invalidates paint-layer painting optimizations, such as subsequence caching
   // and empty paint phase optimizations if clips from the context have changed.
   ALWAYS_INLINE void InvalidatePaintLayerOptimizationsIfNeeded(
       const LayoutObject&,
       PrePaintTreeWalkContext&);
 
+  // Returns true if we should force checking subtree invalidation flags.
+  ALWAYS_INLINE bool InvalidatePaintLayerOptimizationsForFragment(
+      const LayoutObject&,
+      const PaintLayer* ancestor_transformed_or_root_paint_layer,
+      const PaintPropertyTreeBuilderFragmentContext&,
+      FragmentData&);
+
   // Returns the clip applied to children for the given containing block context
   // + effect, in the space of ancestorState adjusted by ancestorPaintOffset.
   ALWAYS_INLINE LayoutRect ComputeClipRectForContext(
       const PaintPropertyTreeBuilderFragmentContext::ContainingBlockContext&,
       const EffectPaintPropertyNode*,
       const PropertyTreeState& ancestor_state,
       const LayoutPoint& ancestor_paint_offset);
 
   bool ALWAYS_INLINE
   NeedsTreeBuilderContextUpdate(const FrameView&,
                                 const PrePaintTreeWalkContext&);
   bool ALWAYS_INLINE
   NeedsTreeBuilderContextUpdate(const LayoutObject&,
                                 const PrePaintTreeWalkContext&);
 
+  static void ClearPreviousClipRectsForTesting(const LayoutObject&);
+
   PaintPropertyTreeBuilder property_tree_builder_;
   PaintInvalidator paint_invalidator_;
+
+  FRIEND_TEST_ALL_PREFIXES(PrePaintTreeWalkTest, ClipRects);
 };
 
 }  // namespace blink
 
 #endif  // PrePaintTreeWalk_h