Remove caching of contents paint properties

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

 // Copyright 2017 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/RarePaintData.h"
 
 #include "core/paint/ObjectPaintProperties.h"
 
 namespace blink {
 
 RarePaintData::RarePaintData() {}
 
 RarePaintData::~RarePaintData() {}
 
 ObjectPaintProperties& RarePaintData::EnsurePaintProperties() {
   if (!paint_properties_)
     paint_properties_ = ObjectPaintProperties::Create();
   return *paint_properties_.get();
 }
 
 void RarePaintData::ClearLocalBorderBoxProperties() {
   local_border_box_properties_ = nullptr;
-
-  // The contents properties are based on the border box so we need to clear
-  // the cached value.
-  contents_properties_ = nullptr;
 }
 
 void RarePaintData::SetLocalBorderBoxProperties(PropertyTreeState& state) {
   if (!local_border_box_properties_)
     local_border_box_properties_ = WTF::MakeUnique<PropertyTreeState>(state);
   else
     *local_border_box_properties_ = state;
-
-  // The contents properties are based on the border box so we need to clear
-  // the cached value.
-  contents_properties_ = nullptr;
 }
 
-static std::unique_ptr<PropertyTreeState> ComputeContentsProperties(
-    PropertyTreeState* local_border_box_properties,
-    ObjectPaintProperties* paint_properties) {
-  if (!local_border_box_properties)
-    return nullptr;
-
-  std::unique_ptr<PropertyTreeState> contents =
-      WTF::MakeUnique<PropertyTreeState>(*local_border_box_properties);
-
-  if (paint_properties) {
-    if (paint_properties->ScrollTranslation())
-      contents->SetTransform(paint_properties->ScrollTranslation());
-    if (paint_properties->OverflowClip())
-      contents->SetClip(paint_properties->OverflowClip());
-    else if (paint_properties->CssClip())
-      contents->SetClip(paint_properties->CssClip());
+PropertyTreeState RarePaintData::ContentsProperties() const {
+  DCHECK(local_border_box_properties_);
+  PropertyTreeState contents(*local_border_box_properties_);
+  if (paint_properties_) {
+    if (paint_properties_->ScrollTranslation())
+      contents.SetTransform(paint_properties_->ScrollTranslation());
+    if (paint_properties_->OverflowClip())
+      contents.SetClip(paint_properties_->OverflowClip());
+    else if (paint_properties_->CssClip())
+      contents.SetClip(paint_properties_->CssClip());
   }
 
   // TODO(chrishtr): cssClipFixedPosition needs to be handled somehow.
 
   return contents;
 }
 
-const PropertyTreeState* RarePaintData::ContentsProperties() const {
-  if (!contents_properties_) {
-    if (local_border_box_properties_) {
-      contents_properties_ = ComputeContentsProperties(
-          local_border_box_properties_.get(), paint_properties_.get());
-    }
-  } else {
-#if DCHECK_IS_ON()
-    // Check that the cached contents properties are valid by checking that they
-    // do not change if recalculated.
-    DCHECK(local_border_box_properties_);
-    std::unique_ptr<PropertyTreeState> old_properties =
-        std::move(contents_properties_);
-    contents_properties_ = ComputeContentsProperties(
-        local_border_box_properties_.get(), paint_properties_.get());
-    DCHECK(*contents_properties_ == *old_properties);
-#endif
-  }
-  return contents_properties_.get();
-}
-
 }  // namespace blink