Store PaintPropertyTreeBuilderContext inline

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

Index: third_party/WebKit/Source/core/paint/PrePaintTreeWalk.cpp
diff --git a/third_party/WebKit/Source/core/paint/PrePaintTreeWalk.cpp b/third_party/WebKit/Source/core/paint/PrePaintTreeWalk.cpp
index d6e05ed112949823acd0f2522df469b6bab35b3c..24300b7bf5068b5e3b96729f9962677f66588587 100644
--- a/third_party/WebKit/Source/core/paint/PrePaintTreeWalk.cpp
+++ b/third_party/WebKit/Source/core/paint/PrePaintTreeWalk.cpp
@@ -15,25 +15,23 @@
 namespace blink {
 
 struct PrePaintTreeWalkContext {
+  USING_FAST_MALLOC(PrePaintTreeWalkContext);
+
+ public:
   PrePaintTreeWalkContext()
-      : treeBuilderContext(
-            WTF::wrapUnique(new PaintPropertyTreeBuilderContext)),
-        paintInvalidatorContext(*treeBuilderContext),
+      : treeBuilderContext(),
+        paintInvalidatorContext(treeBuilderContext),
         ancestorOverflowPaintLayer(nullptr),
         ancestorTransformedOrRootPaintLayer(nullptr) {}
   PrePaintTreeWalkContext(const PrePaintTreeWalkContext& parentContext)
-      : treeBuilderContext(WTF::wrapUnique(new PaintPropertyTreeBuilderContext(
-            *parentContext.treeBuilderContext))),
-        paintInvalidatorContext(*treeBuilderContext,
+      : treeBuilderContext(parentContext.treeBuilderContext),
+        paintInvalidatorContext(treeBuilderContext,
                                 parentContext.paintInvalidatorContext),
         ancestorOverflowPaintLayer(parentContext.ancestorOverflowPaintLayer),
         ancestorTransformedOrRootPaintLayer(
             parentContext.ancestorTransformedOrRootPaintLayer) {}
 
-  // PaintPropertyTreeBuilderContext is large and can lead to stack overflows
-  // when recursion is deep so this context object is allocated on the heap.
-  // See: https://crbug.com/698653.
-  std::unique_ptr<PaintPropertyTreeBuilderContext> treeBuilderContext;
+  PaintPropertyTreeBuilderContext treeBuilderContext;
 
   PaintInvalidatorContext paintInvalidatorContext;
 
@@ -49,7 +47,7 @@ void PrePaintTreeWalk::walk(FrameView& rootFrame) {
          DocumentLifecycle::InPrePaint);
 
   PrePaintTreeWalkContext initialContext;
-  m_propertyTreeBuilder.setupInitialContext(*initialContext.treeBuilderContext);
+  m_propertyTreeBuilder.setupInitialContext(initialContext.treeBuilderContext);
   initialContext.ancestorTransformedOrRootPaintLayer =
       rootFrame.layoutView()->layer();
 
@@ -73,8 +71,7 @@ void PrePaintTreeWalk::walk(FrameView& frameView,
   PrePaintTreeWalkContext context(parentContext);
   // ancestorOverflowLayer does not cross frame boundaries.
   context.ancestorOverflowPaintLayer = nullptr;
-  m_propertyTreeBuilder.updateProperties(frameView,
-                                         *context.treeBuilderContext);
+  m_propertyTreeBuilder.updateProperties(frameView, context.treeBuilderContext);
   m_paintInvalidator.invalidatePaintIfNeeded(frameView,
                                              context.paintInvalidatorContext);
 
@@ -186,8 +183,8 @@ void PrePaintTreeWalk::invalidatePaintLayerOptimizationsIfNeeded(
 
   FloatClipRect clipRect;
   const EffectPaintPropertyNode* effect =
-      context.treeBuilderContext->currentEffect;
-  computeClipRectForContext(context.treeBuilderContext->current, effect,
+      context.treeBuilderContext.currentEffect;
+  computeClipRectForContext(context.treeBuilderContext.current, effect,
                             ancestorState, ancestorPaintOffset, hasClip,
                             clipRect);
   clipRects->setOverflowClipRect(clipRect);
@@ -197,7 +194,7 @@ void PrePaintTreeWalk::invalidatePaintLayerOptimizationsIfNeeded(
       << "rect= " << clipRects->overflowClipRect().toString();
 #endif
 
-  computeClipRectForContext(context.treeBuilderContext->fixedPosition, effect,
+  computeClipRectForContext(context.treeBuilderContext.fixedPosition, effect,
                             ancestorState, ancestorPaintOffset, hasClip,
                             clipRect);
   clipRects->setFixedClipRect(clipRect);
@@ -206,8 +203,8 @@ void PrePaintTreeWalk::invalidatePaintLayerOptimizationsIfNeeded(
       << " fixed=" << clipRects->fixedClipRect().toString();
 #endif
 
-  computeClipRectForContext(context.treeBuilderContext->absolutePosition,
-                            effect, ancestorState, ancestorPaintOffset, hasClip,
+  computeClipRectForContext(context.treeBuilderContext.absolutePosition, effect,
+                            ancestorState, ancestorPaintOffset, hasClip,
                             clipRect);
   clipRects->setPosClipRect(clipRect);
 #ifdef CHECK_CLIP_RECTS
@@ -237,7 +234,7 @@ bool PrePaintTreeWalk::shouldEndWalkBefore(
   return (
       !object.needsPaintPropertyUpdate() &&
       !object.descendantNeedsPaintPropertyUpdate() &&
-      !context.treeBuilderContext->forceSubtreeUpdate &&
+      !context.treeBuilderContext.forceSubtreeUpdate &&
       !context.paintInvalidatorContext.forcedSubtreeInvalidationFlags &&
       !object
            .shouldCheckForPaintInvalidationRegardlessOfPaintInvalidationState());
@@ -255,11 +252,11 @@ void PrePaintTreeWalk::walk(const LayoutObject& object,
   updateAuxiliaryObjectProperties(object, context);
 
   m_propertyTreeBuilder.updatePropertiesForSelf(object,
-                                                *context.treeBuilderContext);
+                                                context.treeBuilderContext);
   m_paintInvalidator.invalidatePaintIfNeeded(object,
                                              context.paintInvalidatorContext);
-  m_propertyTreeBuilder.updatePropertiesForChildren(
-      object, *context.treeBuilderContext);
+  m_propertyTreeBuilder.updatePropertiesForChildren(object,
+                                                    context.treeBuilderContext);
 
   invalidatePaintLayerOptimizationsIfNeeded(object, context);
 
@@ -276,11 +273,11 @@ void PrePaintTreeWalk::walk(const LayoutObject& object,
     const LayoutPart& layoutPart = toLayoutPart(object);
     FrameViewBase* frameViewBase = layoutPart.frameViewBase();
     if (frameViewBase && frameViewBase->isFrameView()) {
-      context.treeBuilderContext->current.paintOffset +=
+      context.treeBuilderContext.current.paintOffset +=
           layoutPart.replacedContentRect().location() -
           frameViewBase->frameRect().location();
-      context.treeBuilderContext->current.paintOffset =
-          roundedIntPoint(context.treeBuilderContext->current.paintOffset);
+      context.treeBuilderContext.current.paintOffset =
+          roundedIntPoint(context.treeBuilderContext.current.paintOffset);
       walk(*toFrameView(frameViewBase), context);
     }
     // TODO(pdr): Investigate RemoteFrameView (crbug.com/579281).