[RootLayerScrolls] Fix frame scrolling layer in ScrollingCoordinator

third_party/WebKit/Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 2574 matching lines @@
 
 IntRect FrameView::scrollableAreaBoundingBox() const {
   LayoutPartItem ownerLayoutItem = frame().ownerLayoutItem();
   if (ownerLayoutItem.isNull())
     return frameRect();
 
   return ownerLayoutItem.absoluteContentQuad(TraverseDocumentBoundaries)
       .enclosingBoundingBox();
 }
 
-bool FrameView::isScrollable() {
+bool FrameView::isScrollable() const {
   return getScrollingReasons() == Scrollable;
 }
 
 bool FrameView::isProgrammaticallyScrollable() {
   return !m_inUpdateScrollbars;
 }
 
 FrameView::ScrollingReasons FrameView::getScrollingReasons() const {
   // Check for:
   // 1) If there an actual overflow.
@@ skipping 21 matching lines @@
   calculateScrollbarModes(horizontalMode, verticalMode,
                           RulesFromWebContentOnly);
   if (horizontalMode == ScrollbarAlwaysOff &&
       verticalMode == ScrollbarAlwaysOff)
     return NotScrollableExplicitlyDisabled;
 
   return Scrollable;
 }
 
 void FrameView::updateParentScrollableAreaSet() {
+  if (RuntimeEnabledFeatures::rootLayerScrollingEnabled())
+    return;
+
   // That ensures that only inner frames are cached.
   FrameView* parentFrameView = this->parentFrameView();
   if (!parentFrameView)
     return;
 
   if (!isScrollable()) {
     parentFrameView->removeScrollableArea(this);
     return;
   }
 
@@ skipping 1005 matching lines @@
   updateParentScrollableAreaSet();
   setupRenderThrottling();
 
   if (parentFrameView())
     m_subtreeThrottled = parentFrameView()->canThrottleRendering();
 }
 
 void FrameView::removeChild(Widget* child) {
   ASSERT(child->parent() == this);
 
-  if (child->isFrameView())
+  if (child->isFrameView() &&
+      !RuntimeEnabledFeatures::rootLayerScrollingEnabled())
     removeScrollableArea(toFrameView(child));
 
   child->setParent(0);
   m_children.remove(child);
 }
 
 bool FrameView::visualViewportSuppliesScrollbars() {
   // On desktop, we always use the layout viewport's scrollbars.
   if (!m_frame->settings() || !m_frame->settings()->getViewportEnabled() ||
       !m_frame->document() || !m_frame->host())
@@ skipping 1208 matching lines @@
   if (!page()->settings().getThreadedScrollingEnabled())
     reasons |= MainThreadScrollingReason::kThreadedScrollingDisabled;
 
   if (!frame.isLocalFrame())
     return;
 
   if (!toLocalFrame(frame).view()->layerForScrolling())
     return;
 
   reasons |= toLocalFrame(frame).view()->mainThreadScrollingReasonsPerFrame();
-  if (WebLayer* scrollLayer =
-          toLocalFrame(frame).view()->layerForScrolling()->platformLayer()) {
-    if (reasons) {
-      scrollLayer->addMainThreadScrollingReasons(reasons);
-    } else {
-      // Clear all main thread scrolling reasons except the one that's set
-      // if there is a running scroll animation.
-      scrollLayer->clearMainThreadScrollingReasons(
-          ~MainThreadScrollingReason::kHandlingScrollFromMainThread);
+  if (GraphicsLayer* layerForScrolling = toLocalFrame(frame)
+                                             .view()
+                                             ->layoutViewportScrollableArea()
+                                             ->layerForScrolling()) {
+    if (WebLayer* platformLayerForScrolling =
+            layerForScrolling->platformLayer()) {
+      if (reasons) {
+        platformLayerForScrolling->addMainThreadScrollingReasons(reasons);
+      } else {
+        // Clear all main thread scrolling reasons except the one that's set
+        // if there is a running scroll animation.
+        platformLayerForScrolling->clearMainThreadScrollingReasons(
+            ~MainThreadScrollingReason::kHandlingScrollFromMainThread);
+      }
     }
   }
 
   Frame* child = frame.tree().firstChild();
   while (child) {
     updateSubFrameScrollOnMainReason(*child, reasons);
     child = child->tree().nextSibling();
   }
 
   if (frame.isMainFrame())
@@ skipping 175 matching lines @@
     std::unique_ptr<CompositorAnimationTimeline> timeline) {
   m_animationTimeline = std::move(timeline);
 }
 
 void FrameView::setAnimationHost(
     std::unique_ptr<CompositorAnimationHost> host) {
   m_animationHost = std::move(host);
 }
 
 }  // namespace blink