Remove RootLayerScrolling REF.

This removes the entry in runtime_enabled_features.json5 along with the
two remaining uses of it in LocalFrameView.

Bug: 823365
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Ic220dc9dc67c658900619f7f89f83ffce226e4dd
Reviewed-on: https://chromium-review.googlesource.com/1073387
Commit-Queue: Steve Kobes <skobes@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561882}

third_party/blink/renderer/core/frame/local_frame_view.cc

@@ -607,8 +607,6 @@ void LocalFrameView::SetFrameRect(const IntRect& unclamped_frame_rect) {
 
   FrameRectsChanged();
 
-  UpdateParentScrollableAreaSet();
-
   if (auto* layout_view = GetLayoutView())
     layout_view->SetMayNeedPaintInvalidation();
 
@@ -788,17 +786,7 @@ void LocalFrameView::AdjustViewSize() {
     return;
 
   DCHECK_EQ(frame_->View(), this);
-
-  const IntRect rect = layout_view->DocumentRect();
-  const IntSize& size = rect.Size();
-
-  if (!RuntimeEnabledFeatures::RootLayerScrollingEnabled()) {
-    const IntPoint origin(-rect.X(), -rect.Y());
-    if (ScrollOrigin() != origin)
-      SetScrollOrigin(origin);
-  }
-
-  SetLayoutOverflowSize(size);
+  SetLayoutOverflowSize(layout_view->DocumentRect().Size());
 }
 
 void LocalFrameView::AdjustViewSizeAndLayout() {
@@ -1242,8 +1230,6 @@ void LocalFrameView::UpdateLayout() {
 
       PerformLayout(in_subtree_layout);
 
-      UpdateParentScrollableAreaSet();
-
       IntSize new_size(Size());
       if (old_size != new_size) {
         SetNeedsLayout();
@@ -2699,23 +2685,6 @@ LocalFrameView::ScrollingReasons LocalFrameView::GetScrollingReasons() const {
   return kScrollable;
 }
 
-void LocalFrameView::UpdateParentScrollableAreaSet() {
-  if (RuntimeEnabledFeatures::RootLayerScrollingEnabled())
-    return;
-
-  // That ensures that only inner frames are cached.
-  LocalFrameView* parent_frame_view = ParentFrameView();
-  if (!parent_frame_view)
-    return;
-
-  if (!IsScrollable()) {
-    parent_frame_view->RemoveScrollableArea(this);
-    return;
-  }
-
-  parent_frame_view->AddScrollableArea(this);
-}
-
 bool LocalFrameView::ShouldSuspendScrollAnimations() const {
   return !frame_->GetDocument()->LoadEventFinished();
 }
@@ -4123,7 +4092,6 @@ void LocalFrameView::AttachToLayout() {
   CHECK(parent_);
   if (parent_->IsVisible())
     SetParentVisible(true);
-  UpdateParentScrollableAreaSet();
   SetupRenderThrottling();
   subtree_throttled_ = ParentFrameView()->CanThrottleRendering();
 
@@ -5048,7 +5016,6 @@ void LocalFrameView::Show() {
       GetScrollingContext()->SetScrollGestureRegionIsDirty(true);
     }
     SetNeedsCompositingUpdate(kCompositingUpdateRebuildTree);
-    UpdateParentScrollableAreaSet();
     if (IsParentVisible()) {
       ForAllChildViewsAndPlugins(
           [](EmbeddedContentView& embedded_content_view) {
@@ -5072,7 +5039,6 @@ void LocalFrameView::Hide() {
       GetScrollingContext()->SetScrollGestureRegionIsDirty(true);
     }
     SetNeedsCompositingUpdate(kCompositingUpdateRebuildTree);
-    UpdateParentScrollableAreaSet();
   }
 }
 

third_party/blink/renderer/core/frame/local_frame_view.h

@@ -1040,8 +1040,6 @@ class CORE_EXPORT LocalFrameView final
   bool WasViewportResized();
   void SendResizeEventIfNeeded();
 
-  void UpdateParentScrollableAreaSet();
-
   void ScheduleUpdatePluginsIfNecessary();
   void UpdatePluginsTimerFired(TimerBase*);
   bool UpdatePlugins();

third_party/blink/renderer/core/paint/box_paint_invalidator.cc

@@ -207,8 +207,7 @@ bool BoxPaintInvalidator::ShouldFullyInvalidateBackgroundOnLayoutOverflowChange(
 bool BoxPaintInvalidator::ViewBackgroundShouldFullyInvalidate() const {
   DCHECK(box_.IsLayoutView());
   // Fixed attachment background is handled in LayoutView::layout().
-  // TODO(wangxianzhu): Combine code for fixed-attachment background when we
-  // enable rootLayerScrolling permanently.
+  // TODO(wangxianzhu): Combine code for fixed-attachment background.
   if (box_.StyleRef().HasEntirelyFixedBackground())
     return false;
 

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -1071,12 +1071,6 @@
       name: "RestrictCanRequestURLCharacterSet",
       status: "stable",
     },
-    // Handles frame scrolling via the root PaintLayer instead of the FrameView.
-    // The master bug for the root layer scrolling project is crbug.com/417782.
-    {
-      name: "RootLayerScrolling",
-      status: "stable",
-    },
     {
       name: "RtcPeerConnectionId",
       origin_trial_feature_name: "RtcPeerConnectionId",