Make PrePaintTreeWalkContext::treeBuilderContext a unique_ptr

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 77 matching lines @@
   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();
+  void setupInitialContext(PaintPropertyTreeBuilderContext&);
   // 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.,
@@ skipping 39 matching lines @@
       const LayoutObject&,
       PaintPropertyTreeBuilderContext&);
   ALWAYS_INLINE static void updateOutOfFlowContext(
       const LayoutObject&,
       PaintPropertyTreeBuilderContext&);
 };
 
 }  // namespace blink
 
 #endif  // PaintPropertyTreeBuilder_h