Early-out from the prepaint tree walk

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.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 PaintPropertyTreeBuilder_h
 #define PaintPropertyTreeBuilder_h
 
 #include "platform/geometry/LayoutPoint.h"
 #include "platform/graphics/paint/ClipPaintPropertyNode.h"
 #include "platform/graphics/paint/EffectPaintPropertyNode.h"
@@ skipping 59 matching lines @@
   // Therefore, we don't need extra bookkeeping for effect nodes and can
   // generate the effect tree from a DOM-order traversal.
   const EffectPaintPropertyNode* currentEffect = nullptr;
   // Some effects are spatial, i.e. may refer to input pixels outside of output
   // clip. The cull rect for its input shall be derived from its output clip.
   // This variable represents the input cull of current effect, also serves as
   // output clip of child effects that don't have a hard clip.
   const ClipPaintPropertyNode* inputClipOfCurrentEffect = nullptr;
 
   bool isUnderMultiColumnSpanner = false;
+
+  // True if a change has forced all properties in a subtree to be updated. This
+  // can be set due to paint offset changes or when the structure of the
+  // property tree changes (i.e., a node is added or removed).
+  bool forceSubtreeUpdate = false;
 };
 
 // Creates paint property tree nodes for special things in the layout tree.
 // Special things include but not limit to: overflow clip, transform, fixed-pos,
 // animation, mask, filter, ... etc.
 // It expects to be invoked for each layout tree node in DOM order during
 // InPrePaint phase.
 class PaintPropertyTreeBuilder {
  public:
   PaintPropertyTreeBuilderContext setupInitialContext();
@@ skipping 16 matching lines @@
   static void updateTransform(const LayoutObject&,
                               PaintPropertyTreeBuilderContext&);
   static void updateTransformForNonRootSVG(const LayoutObject&,
                                            PaintPropertyTreeBuilderContext&);
   static void updateEffect(const LayoutObject&,
                            PaintPropertyTreeBuilderContext&);
   static void updateCssClip(const LayoutObject&,
                             PaintPropertyTreeBuilderContext&);
   static void updateLocalBorderBoxContext(const LayoutObject&,
                                           PaintPropertyTreeBuilderContext&);
-  static void updateScrollbarPaintOffset(
-      const LayoutObject&,
-      const PaintPropertyTreeBuilderContext&);
+  static void updateScrollbarPaintOffset(const LayoutObject&,
+                                         PaintPropertyTreeBuilderContext&);
   static void updateOverflowClip(const LayoutObject&,
                                  PaintPropertyTreeBuilderContext&);
   static void updatePerspective(const LayoutObject&,
                                 PaintPropertyTreeBuilderContext&);
   static void updateSvgLocalToBorderBoxTransform(
       const LayoutObject&,
       PaintPropertyTreeBuilderContext&);
   static void updateScrollAndScrollTranslation(
       const LayoutObject&,
       PaintPropertyTreeBuilderContext&);
   static void updateOutOfFlowContext(const LayoutObject&,
                                      PaintPropertyTreeBuilderContext&);
 };
 
 }  // namespace blink
 
 #endif  // PaintPropertyTreeBuilder_h