Move RarePaintData to its own file

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 (!m_paintProperties)
+    m_paintProperties = ObjectPaintProperties::create();
+  return *m_paintProperties.get();
+}
+
+void RarePaintData::clearLocalBorderBoxProperties() {
+  m_localBorderBoxProperties = nullptr;
+
+  // The contents properties are based on the border box so we need to clear
+  // the cached value.
+  m_contentsProperties = nullptr;
+}
+
+void RarePaintData::setLocalBorderBoxProperties(PropertyTreeState& state) {
+  if (!m_localBorderBoxProperties)
+    m_localBorderBoxProperties = WTF::makeUnique<PropertyTreeState>(state);
+  else
+    *m_localBorderBoxProperties = state;
+
+  // The contents properties are based on the border box so we need to clear
+  // the cached value.
+  m_contentsProperties = nullptr;
+}
+
+static std::unique_ptr<PropertyTreeState> computeContentsProperties(
+    PropertyTreeState* localBorderBoxProperties,
+    ObjectPaintProperties* paintProperties) {
+  if (!localBorderBoxProperties)
+    return nullptr;
+
+  std::unique_ptr<PropertyTreeState> contents =
+      WTF::makeUnique<PropertyTreeState>(*localBorderBoxProperties);
+
+  if (paintProperties) {
+    if (paintProperties->scrollTranslation())
+      contents->setTransform(paintProperties->scrollTranslation());
+    if (paintProperties->overflowClip())
+      contents->setClip(paintProperties->overflowClip());
+    else if (paintProperties->cssClip())
+      contents->setClip(paintProperties->cssClip());
+  }
+
+  // TODO(chrishtr): cssClipFixedPosition needs to be handled somehow.
+
+  return contents;
+}
+
+const PropertyTreeState* RarePaintData::contentsProperties() const {
+  if (!m_contentsProperties) {
+    if (m_localBorderBoxProperties) {
+      m_contentsProperties = computeContentsProperties(
+          m_localBorderBoxProperties.get(), m_paintProperties.get());
+    }
+  } else {
+#if DCHECK_IS_ON()
+    // Check that the cached contents properties are valid by checking that they
+    // do not change if recalculated.
+    DCHECK(m_localBorderBoxProperties);
+    std::unique_ptr<PropertyTreeState> oldProperties =
+        std::move(m_contentsProperties);
+    m_contentsProperties = computeContentsProperties(
+        m_localBorderBoxProperties.get(), m_paintProperties.get());
+    DCHECK(*m_contentsProperties == *oldProperties);
+#endif
+  }
+  return m_contentsProperties.get();
+}
+
+}  // namespace blink