Make PrePaintTreeWalkContext::treeBuilderContext a unique_ptr

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp

 // 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.
 
 #include "core/paint/PaintPropertyTreeBuilder.h"
 
 #include <memory>
 #include "core/dom/DOMNodeIds.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/layout/LayoutInline.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/compositing/CompositingReasonFinder.h"
 #include "core/layout/svg/LayoutSVGResourceMasker.h"
 #include "core/layout/svg/LayoutSVGRoot.h"
 #include "core/layout/svg/SVGLayoutSupport.h"
 #include "core/layout/svg/SVGResources.h"
 #include "core/layout/svg/SVGResourcesCache.h"
 #include "core/paint/FindPropertiesNeedingUpdate.h"
 #include "core/paint/ObjectPaintProperties.h"
 #include "core/paint/PaintLayer.h"
 #include "core/paint/SVGRootPainter.h"
 #include "platform/transforms/TransformationMatrix.h"
 #include "wtf/PtrUtil.h"
 
 namespace blink {
 
-PaintPropertyTreeBuilderContext
-PaintPropertyTreeBuilder::setupInitialContext() {
-  PaintPropertyTreeBuilderContext context;
+void PaintPropertyTreeBuilder::setupInitialContext(
+    PaintPropertyTreeBuilderContext& context) {
   context.current.clip = context.absolutePosition.clip =
       context.fixedPosition.clip = ClipPaintPropertyNode::root();
   context.currentEffect = EffectPaintPropertyNode::root();
   context.inputClipOfCurrentEffect = ClipPaintPropertyNode::root();
   context.current.transform = context.absolutePosition.transform =
       context.fixedPosition.transform = TransformPaintPropertyNode::root();
   context.current.scroll = context.absolutePosition.scroll =
       context.fixedPosition.scroll = ScrollPaintPropertyNode::root();
-  return context;
 }
 
 // True if a new property was created, false if an existing one was updated.
 static bool updatePreTranslation(
     FrameView& frameView,
     PassRefPtr<const TransformPaintPropertyNode> parent,
     const TransformationMatrix& matrix,
     const FloatPoint3D& origin) {
   DCHECK(!RuntimeEnabledFeatures::rootLayerScrollingEnabled());
   if (auto* existingPreTranslation = frameView.preTranslation()) {
@@ skipping 1076 matching lines @@
   updateOverflowClip(object, context);
   updatePerspective(object, context);
   updateSvgLocalToBorderBoxTransform(object, context);
   updateScrollAndScrollTranslation(object, context);
   updateOutOfFlowContext(object, context);
 
   context.forceSubtreeUpdate |= object.subtreeNeedsPaintPropertyUpdate();
 }
 
 }  // namespace blink