Add position sticky main thread scrolling reason [spv2]

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

 // Copyright 2015 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/PaintPropertyTreeBuilder.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/layout/LayoutInline.h"
@@ skipping 324 matching lines @@
 
 void PaintPropertyTreeBuilder::updateMainThreadScrollingReasons(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
 {
     if (object.isBackgroundAttachmentFixedObject()) {
         auto* scrollNode = context.current.scroll;
         while (scrollNode && !scrollNode->hasMainThreadScrollingReasons(MainThreadScrollingReason::kHasBackgroundAttachmentFixedObjects)) {
             scrollNode->addMainThreadScrollingReasons(MainThreadScrollingReason::kHasBackgroundAttachmentFixedObjects);
             scrollNode = scrollNode->parent();
         }
     }
+    if (object.styleRef().position() == StickyPosition) {
+        auto* scrollNode = context.current.scroll;
+        while (scrollNode && !scrollNode->hasMainThreadScrollingReasons(MainThreadScrollingReason::kHasStickyPositionObjects)) {
+            scrollNode->addMainThreadScrollingReasons(MainThreadScrollingReason::kHasStickyPositionObjects);
+            scrollNode = scrollNode->parent();
+        }
+    }
 }
 
 void PaintPropertyTreeBuilder::updateOverflowClip(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
 {
     if (!object.isBox())
         return;
     const LayoutBox& box = toLayoutBox(object);
 
     // The <input> elements can't have contents thus CSS overflow property doesn't apply.
     // However for layout purposes we do generate child layout objects for them, e.g. button label.
@@ skipping 215 matching lines @@
         return;
 
     updateOverflowClip(object, context);
     updatePerspective(object, context);
     updateSvgLocalToBorderBoxTransform(object, context);
     updateScrollAndScrollTranslation(object, context);
     updateOutOfFlowContext(object, context);
 }
 
 } // namespace blink