Revert of Implement overlay scrollbar fade out for non-composited scrollers.

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

Index: third_party/WebKit/Source/core/frame/FrameView.cpp
diff --git a/third_party/WebKit/Source/core/frame/FrameView.cpp b/third_party/WebKit/Source/core/frame/FrameView.cpp
index f639d80f6d7e0c34cdf33d8a3891c8987b2a5f9e..873fb8d31e5924eb1237dc395d07d2df7a2c25a1 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameView.cpp
@@ -319,9 +319,9 @@
   // from non-GC'd objects and RootFrameViewport will still have a pointer to
   // this class.
   if (m_viewportScrollableArea)
-    m_viewportScrollableArea->clearScrollableArea();
-
-  clearScrollableArea();
+    m_viewportScrollableArea->clearScrollAnimators();
+
+  clearScrollAnimators();
 
   // Destroy |m_autoSizeInfo| as early as possible, to avoid dereferencing
   // partially destroyed |this| via |m_autoSizeInfo->m_frameView|.
@@ -1501,7 +1501,6 @@
 void FrameView::viewportSizeChanged(bool widthChanged, bool heightChanged) {
   DCHECK(widthChanged || heightChanged);
 
-  showOverlayScrollbars();
   if (RuntimeEnabledFeatures::rootLayerScrollingEnabled()) {
     // The background must be repainted when the FrameView is resized, even if
     // the initial containing block does not change (so we can't rely on layout
@@ -2439,8 +2438,6 @@
 }
 
 void FrameView::scrollbarVisibilityChanged() {
-  // Scrollbar enabled state is set from updateScrollbarGeometry.
-  updateScrollbarGeometry();
   LayoutViewItem viewItem = layoutViewItem();
   if (!viewItem.isNull())
     viewItem.clearHitTestCache();
@@ -3658,8 +3655,6 @@
   if (scrollDelta.isZero())
     return;
 
-  showOverlayScrollbars();
-
   if (RuntimeEnabledFeatures::rootLayerScrollingEnabled()) {
     // Don't scroll the FrameView!
     ASSERT_NOT_REACHED();
@@ -3880,6 +3875,10 @@
   if (m_needsScrollbarsUpdate || needsScrollbarReconstruction() ||
       scrollOriginChanged())
     updateScrollbars();
+}
+
+void FrameView::didChangeScrollbarsHidden() {
+  updateScrollbars();
 }
 
 void FrameView::updateScrollbars() {