Introduce PaintPropertyTreeBuilderFragmentContext and use it throughout.

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"
 #include "platform/graphics/paint/ScrollPaintPropertyNode.h"
 #include "platform/graphics/paint/TransformPaintPropertyNode.h"
 #include "platform/wtf/RefPtr.h"
 
 namespace blink {
 
 class FrameView;
 class LayoutBoxModelObject;
 class LayoutObject;
 
 // The context for PaintPropertyTreeBuilder.
 // It's responsible for bookkeeping tree state in other order, for example, the
 // most recent position container seen.
-struct PaintPropertyTreeBuilderContext {
-  USING_FAST_MALLOC(PaintPropertyTreeBuilderContext);
+struct PaintPropertyTreeBuilderFragmentContext {
+  USING_FAST_MALLOC(PaintPropertyTreeBuilderFragmentContext);
 
  public:
   // Initializes all property tree nodes to the roots.
-  PaintPropertyTreeBuilderContext();
+  PaintPropertyTreeBuilderFragmentContext();
 
   // State that propagates on the containing block chain (and so is adjusted
   // when an absolute or fixed position object is encountered).
   struct ContainingBlockContext {
     // The combination of a transform and paint offset describes a linear space.
     // When a layout object recur to its children, the main context is expected
     // to refer the object's border box, then the callee will derive its own
     // border box by translating the space with its own layout location.
     const TransformPaintPropertyNode* transform = nullptr;
     LayoutPoint paint_offset;
@@ skipping 21 matching lines @@
   ContainingBlockContext current;
 
   // Separate context for out-of-flow positioned and fixed positioned elements
   // are needed because they don't use DOM parent as their containing block.
   // These additional contexts normally pass through untouched, and are only
   // copied from the main context when the current element serves as the
   // containing block of corresponding positioned descendants.  Overflow clips
   // are also inherited by containing block tree instead of DOM tree, thus they
   // are included in the additional context too.
   ContainingBlockContext absolute_position;
-  const LayoutObject* container_for_absolute_position;
 
   ContainingBlockContext fixed_position;
 
   // This is the same as current.paintOffset except when a floating object has
   // non-block ancestors under its containing block. Paint offsets of the
   // non-block ancestors should not be accumulated for the floating object.
   LayoutPoint paint_offset_for_float;
 
   // The effect hierarchy is applied by the stacking context tree. It is
   // guaranteed that every DOM descendant is also a stacking context descendant.
   // Therefore, we don't need extra bookkeeping for effect nodes and can
   // generate the effect tree from a DOM-order traversal.
   const EffectPaintPropertyNode* current_effect;
   // 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* input_clip_of_current_effect;
+};
+
+struct PaintPropertyTreeBuilderContext {
+  USING_FAST_MALLOC(PaintPropertyTreeBuilderContext);
+
+ public:
+  PaintPropertyTreeBuilderContext()
+      : container_for_absolute_position(nullptr),
+        force_subtree_update(false)
+#if DCHECK_IS_ON()
+        ,
+        is_actually_needed(true)
+#endif
+  {
+  }
+
+  Vector<PaintPropertyTreeBuilderFragmentContext> fragments;
+  const LayoutObject* container_for_absolute_position;
 
   // 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 force_subtree_update;
 
 #if DCHECK_IS_ON()
   // When DCHECK_IS_ON() we create PaintPropertyTreeBuilderContext even if not
   // needed. See FindPaintOffsetAndVisualRectNeedingUpdate.h.
-  bool is_actually_needed = true;
+  bool is_actually_needed;
 #endif
 };
 
 // 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:
   // Update the paint properties for a frame and ensure the context is up to
   // date.
   void UpdateProperties(FrameView&, PaintPropertyTreeBuilderContext&);
 
   // Update the paint properties that affect this object (e.g., properties like
   // paint offset translation) and ensure the context is up to date. Also
   // handles updating the object's paintOffset.
   void UpdatePropertiesForSelf(const LayoutObject&,
                                PaintPropertyTreeBuilderContext&);
   // Update the paint properties that affect children of this object (e.g.,
   // scroll offset transform) and ensure the context is up to date.
   void UpdatePropertiesForChildren(const LayoutObject&,
                                    PaintPropertyTreeBuilderContext&);
 
  private:
-  ALWAYS_INLINE static void UpdatePaintOffset(const LayoutBoxModelObject&,
-                                              PaintPropertyTreeBuilderContext&);
+  ALWAYS_INLINE static void UpdatePaintOffset(
+      const LayoutBoxModelObject&,
+      PaintPropertyTreeBuilderFragmentContext&,
+      const LayoutObject* container_for_absolute_position);
   ALWAYS_INLINE static void UpdatePaintOffsetTranslation(
       const LayoutBoxModelObject&,
-      PaintPropertyTreeBuilderContext&);
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
   ALWAYS_INLINE static void UpdateForObjectLocationAndSize(
       const LayoutObject&,
-      PaintPropertyTreeBuilderContext&);
-  ALWAYS_INLINE static void UpdateTransform(const LayoutObject&,
-                                            PaintPropertyTreeBuilderContext&);
+      const LayoutObject* container_for_absolute_position,
+      bool& is_actually_needed,
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
+  ALWAYS_INLINE static void UpdateTransform(
+      const LayoutObject&,
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
   ALWAYS_INLINE static void UpdateTransformForNonRootSVG(
       const LayoutObject&,
-      PaintPropertyTreeBuilderContext&);
-  ALWAYS_INLINE static void UpdateEffect(const LayoutObject&,
-                                         PaintPropertyTreeBuilderContext&);
-  ALWAYS_INLINE static void UpdateFilter(const LayoutObject&,
-                                         PaintPropertyTreeBuilderContext&);
-  ALWAYS_INLINE static void UpdateCssClip(const LayoutObject&,
-                                          PaintPropertyTreeBuilderContext&);
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
+  ALWAYS_INLINE static void UpdateEffect(
+      const LayoutObject&,
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
+  ALWAYS_INLINE static void UpdateFilter(
+      const LayoutObject&,
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
+  ALWAYS_INLINE static void UpdateCssClip(
+      const LayoutObject&,
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
   ALWAYS_INLINE static void UpdateLocalBorderBoxContext(
       const LayoutObject&,
-      PaintPropertyTreeBuilderContext&);
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
   ALWAYS_INLINE static void UpdateScrollbarPaintOffset(
       const LayoutObject&,
-      PaintPropertyTreeBuilderContext&);
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
   ALWAYS_INLINE static void UpdateOverflowClip(
       const LayoutObject&,
-      PaintPropertyTreeBuilderContext&);
-  ALWAYS_INLINE static void UpdatePerspective(const LayoutObject&,
-                                              PaintPropertyTreeBuilderContext&);
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
+  ALWAYS_INLINE static void UpdatePerspective(
+      const LayoutObject&,
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
   ALWAYS_INLINE static void UpdateSvgLocalToBorderBoxTransform(
       const LayoutObject&,
-      PaintPropertyTreeBuilderContext&);
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
   ALWAYS_INLINE static void UpdateScrollAndScrollTranslation(
       const LayoutObject&,
-      PaintPropertyTreeBuilderContext&);
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
   ALWAYS_INLINE static void UpdateOutOfFlowContext(
       const LayoutObject&,
-      PaintPropertyTreeBuilderContext&);
+      PaintPropertyTreeBuilderFragmentContext&,
+      bool& force_subtree_update);
 
   // Ensure the ObjectPaintProperties object is created if it will be needed, or
   // cleared otherwise.
   ALWAYS_INLINE static void UpdatePaintProperties(
       const LayoutObject&,
       PaintPropertyTreeBuilderContext&);
 };
 
 }  // namespace blink
 
 #endif  // PaintPropertyTreeBuilder_h