Skip paint property update and visual rect update if no geometry change

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

 // 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()
+
+#include "core/frame/FrameView.h"
+#include "core/layout/LayoutObject.h"
+#include "core/paint/ObjectPaintProperties.h"
+#include "core/paint/PaintPropertyTreeBuilder.h"
+
 namespace blink {
 
 // This file contains two scope classes for catching cases where paint
 // properties needed an update but were not marked as such. If paint properties
 // will change, the object must be marked as needing a paint property update
 // using {FrameView, LayoutObject}::setNeedsPaintPropertyUpdate() or by forcing
 // a subtree update (see: PaintPropertyTreeBuilderContext::forceSubtreeUpdate).
 //
 // Both scope classes work by recording the paint property state of an object
 // before rebuilding properties, forcing the properties to get updated, then
@@ skipping 64 matching lines @@
                                  m_frameView->scrollTranslation());
 
     // Restore original clean bit.
     m_frameView->clearNeedsPaintPropertyUpdate();
   }
 
  private:
   Persistent<FrameView> m_frameView;
   bool m_neededPaintPropertyUpdate;
   bool m_neededForcedSubtreeUpdate;
-  RefPtr<TransformPaintPropertyNode> m_originalPreTranslation;
-  RefPtr<ClipPaintPropertyNode> m_originalContentClip;
-  RefPtr<TransformPaintPropertyNode> m_originalScrollTranslation;
+  RefPtr<const TransformPaintPropertyNode> m_originalPreTranslation;
+  RefPtr<const ClipPaintPropertyNode> m_originalContentClip;
+  RefPtr<const TransformPaintPropertyNode> m_originalScrollTranslation;
 };
 
 #define DCHECK_OBJECT_PROPERTY_EQ(object, original, updated)            \
   CHECK_PROPERTY_EQ("the layout object (" << object.debugName() << ")", \
                     original, updated)
 
 class FindObjectPropertiesNeedingUpdateScope {
  public:
   FindObjectPropertiesNeedingUpdateScope(
       const LayoutObject& object,
@@ skipping 13 matching lines @@
     if (const auto* properties = m_object.paintProperties())
       m_originalProperties = properties->clone();
 
     if (const auto* localBorderBox = m_object.localBorderBoxProperties()) {
       m_originalLocalBorderBoxProperties =
           WTF::wrapUnique(new PropertyTreeState(*localBorderBox));
     }
   }
 
   ~FindObjectPropertiesNeedingUpdateScope() {
+    // Paint offset and paintOffsetTranslation should not change under
+    // FindObjectPropertiesNeedingUpdateScope no matter if we needed paint
+    // property update.
+    DCHECK_OBJECT_PROPERTY_EQ(m_object, &m_originalPaintOffset,
+                              &m_object.paintOffset());
+    const auto* objectProperties = m_object.paintProperties();
+    if (m_originalProperties && objectProperties) {
+      DCHECK_OBJECT_PROPERTY_EQ(m_object,
+                                m_originalProperties->paintOffsetTranslation(),
+                                objectProperties->paintOffsetTranslation());
+    }
+
     // No need to check if an update was already needed.
     if (m_neededPaintPropertyUpdate || m_neededForcedSubtreeUpdate)
       return;
 
     // If these checks fail, the paint properties changed unexpectedly. This is
     // due to missing one of these paint property invalidations:
     // 1) The LayoutObject should have been marked as needing an update with
     //    LayoutObject::setNeedsPaintPropertyUpdate().
     // 2) The PrePaintTreeWalk should have had a forced subtree update (see:
     //    PaintPropertyTreeBuilderContext::forceSubtreeUpdate).
-    DCHECK_OBJECT_PROPERTY_EQ(m_object, &m_originalPaintOffset,
-                              &m_object.paintOffset());
-    const auto* objectProperties = m_object.paintProperties();
     if (m_originalProperties && objectProperties) {
-      DCHECK_OBJECT_PROPERTY_EQ(m_object,
-                                m_originalProperties->paintOffsetTranslation(),
-                                objectProperties->paintOffsetTranslation());
       DCHECK_OBJECT_PROPERTY_EQ(m_object, m_originalProperties->transform(),
                                 objectProperties->transform());
       DCHECK_OBJECT_PROPERTY_EQ(m_object, m_originalProperties->effect(),
                                 objectProperties->effect());
       DCHECK_OBJECT_PROPERTY_EQ(m_object, m_originalProperties->filter(),
                                 objectProperties->filter());
       DCHECK_OBJECT_PROPERTY_EQ(m_object, m_originalProperties->mask(),
                                 objectProperties->mask());
       DCHECK_OBJECT_PROPERTY_EQ(m_object, m_originalProperties->maskClip(),
                                 objectProperties->maskClip());
@@ skipping 52 matching lines @@
   bool m_neededForcedSubtreeUpdate;
   LayoutPoint m_originalPaintOffset;
   std::unique_ptr<const ObjectPaintProperties> m_originalProperties;
   std::unique_ptr<const PropertyTreeState> m_originalLocalBorderBoxProperties;
 };
 
 }  // namespace blink
 #endif  // DCHECK_IS_ON()
 
 #endif  // FindPropertiesNeedingUpdate_h