Implement incremental paint property tree rebuilding

third_party/WebKit/Source/core/paint/FindPropertiesNeedingUpdate.h

Index: third_party/WebKit/Source/core/paint/FindPropertiesNeedingUpdate.h
diff --git a/third_party/WebKit/Source/core/paint/FindPropertiesNeedingUpdate.h b/third_party/WebKit/Source/core/paint/FindPropertiesNeedingUpdate.h
new file mode 100644
index 0000000000000000000000000000000000000000..fb3358b3aa74a4532ceb25d031c6e892b3e722f8
--- /dev/null
+++ b/third_party/WebKit/Source/core/paint/FindPropertiesNeedingUpdate.h
@@ -0,0 +1,144 @@
+// Copyright 2016 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 FindPropertiesNeedingUpdate_h
+#define FindPropertiesNeedingUpdate_h
+
+#if DCHECK_IS_ON()
+namespace blink {
+
+#define DCHECK_PTR_VAL_EQ(ptrA, ptrB) \
+  DCHECK((!!ptrA == !!ptrB) && ((!ptrA && !ptrB) || (*ptrA == *ptrB)));
+
+// This file contains two scope classes for catching cases where paint
+// properties need an update but where not marked as such. If paint properties
+// will change, the object must be marked as needing a paint property update
+// using {FrameView, LayoutObject}::setNeedsPaintPropertyUpdate().
+//
+// Both scope classes work by recording the paint property state of an object
+// before rebuilding properties, forcing the properties to get updated, then
+// checking that the updated properties match the original properties.
+
+class FindFrameViewPropertiesNeedingUpdateScope {
+ public:
+  FindFrameViewPropertiesNeedingUpdateScope(FrameView* frameView)
+      : m_frameView(frameView),
+        m_neededPaintPropertyUpdate(frameView->needsPaintPropertyUpdate()) {
+    // No need to check when already marked as needing an update.
+    if (m_neededPaintPropertyUpdate)
+      return;
+
+    // Mark the properties as needing an update to ensure they are rebuilt.
+    m_frameView->setNeedsPaintPropertyUpdate();
+    if (auto* preTranslation = m_frameView->preTranslation())
+      m_preTranslation = preTranslation->clone();
+    if (auto* contentClip = m_frameView->contentClip())
+      m_contentClip = contentClip->clone();
+    if (auto* scrollTranslation = m_frameView->scrollTranslation())
+      m_scrollTranslation = scrollTranslation->clone();
+    if (auto* scroll = m_frameView->scroll())
+      m_scroll = scroll->clone();
+  }
+
+  ~FindFrameViewPropertiesNeedingUpdateScope() {
+    // No need to check when already marked as needing an update.
+    if (m_neededPaintPropertyUpdate)
+      return;
+
+    // If paint properties are not marked as needing an update but still change,
+    // we are missing a call to FrameView::setNeedsPaintPropertyUpdate().
+    DCHECK_PTR_VAL_EQ(m_preTranslation, m_frameView->preTranslation());
+    DCHECK_PTR_VAL_EQ(m_contentClip, m_frameView->contentClip());
+    DCHECK_PTR_VAL_EQ(m_scrollTranslation, m_frameView->scrollTranslation());
+    DCHECK_PTR_VAL_EQ(m_scroll, m_frameView->scroll());
+    // Restore original clean bit.
+    m_frameView->clearNeedsPaintPropertyUpdate();
+  }
+
+ private:
+  Persistent<FrameView> m_frameView;
+  bool m_neededPaintPropertyUpdate;
+  RefPtr<TransformPaintPropertyNode> m_preTranslation;
+  RefPtr<ClipPaintPropertyNode> m_contentClip;
+  RefPtr<TransformPaintPropertyNode> m_scrollTranslation;
+  RefPtr<ScrollPaintPropertyNode> m_scroll;
+};
+
+class FindObjectPropertiesNeedingUpdateScope {
+ public:
+  FindObjectPropertiesNeedingUpdateScope(const LayoutObject& object)
+      : m_object(object),
+        m_neededPaintPropertyUpdate(object.needsPaintPropertyUpdate()) {
+    // No need to check when already marked as needing an update.
+    if (m_neededPaintPropertyUpdate)
+      return;
+
+    // Mark the properties as needing an update to ensure they are rebuilt.
+    const_cast<LayoutObject&>(m_object).setNeedsPaintPropertyUpdate();
+    if (const auto* properties = m_object.paintProperties())
+      m_properties = properties->clone();
+  }
+
+  ~FindObjectPropertiesNeedingUpdateScope() {
+    // No need to check when already marked as needing an update.
+    if (m_neededPaintPropertyUpdate)
+      return;
+
+    // If paint properties are not marked as needing an update but still change,
+    // we are missing a call to LayoutObject::setNeedsPaintPropertyUpdate().
+    const auto* objectProperties = m_object.paintProperties();
+    if (m_properties && objectProperties) {
+      DCHECK_PTR_VAL_EQ(m_properties->paintOffsetTranslation(),
+                        objectProperties->paintOffsetTranslation());
+      DCHECK_PTR_VAL_EQ(m_properties->transform(),
+                        objectProperties->transform());
+      DCHECK_PTR_VAL_EQ(m_properties->effect(), objectProperties->effect());
+      DCHECK_PTR_VAL_EQ(m_properties->cssClip(), objectProperties->cssClip());
+      DCHECK_PTR_VAL_EQ(m_properties->cssClipFixedPosition(),
+                        objectProperties->cssClipFixedPosition());
+      DCHECK_PTR_VAL_EQ(m_properties->innerBorderRadiusClip(),
+                        objectProperties->innerBorderRadiusClip());
+      DCHECK_PTR_VAL_EQ(m_properties->overflowClip(),
+                        objectProperties->overflowClip());
+      DCHECK_PTR_VAL_EQ(m_properties->perspective(),
+                        objectProperties->perspective());
+      DCHECK_PTR_VAL_EQ(m_properties->svgLocalToBorderBoxTransform(),
+                        objectProperties->svgLocalToBorderBoxTransform());
+      DCHECK_PTR_VAL_EQ(m_properties->scrollTranslation(),
+                        objectProperties->scrollTranslation());
+      DCHECK_PTR_VAL_EQ(m_properties->scrollbarPaintOffset(),
+                        objectProperties->scrollbarPaintOffset());
+      const auto* borderBox = m_properties->localBorderBoxProperties();
+      const auto* objectBorderBox =
+          objectProperties->localBorderBoxProperties();
+      if (borderBox && objectBorderBox) {
+        DCHECK(borderBox->paintOffset == objectBorderBox->paintOffset);
+        DCHECK_EQ(borderBox->propertyTreeState.transform(),
+                  objectBorderBox->propertyTreeState.transform());
+        DCHECK_EQ(borderBox->propertyTreeState.clip(),
+                  objectBorderBox->propertyTreeState.clip());
+        DCHECK_EQ(borderBox->propertyTreeState.effect(),
+                  objectBorderBox->propertyTreeState.effect());
+        DCHECK_EQ(borderBox->propertyTreeState.scroll(),
+                  objectBorderBox->propertyTreeState.scroll());
+      } else {
+        DCHECK_EQ(!!borderBox, !!objectBorderBox);
+      }
+    } else {
+      DCHECK_EQ(!!m_properties, !!objectProperties);
+    }
+    // Restore original clean bit.
+    const_cast<LayoutObject&>(m_object).clearNeedsPaintPropertyUpdate();
+  }
+
+ private:
+  const LayoutObject& m_object;
+  bool m_neededPaintPropertyUpdate;
+  std::unique_ptr<const ObjectPaintProperties> m_properties;
+};
+
+}  // namespace blink
+#endif  // DCHECK_IS_ON()
+
+#endif  // FindPropertiesNeedingUpdate_h