Implement overlay scrollbar fade out for non-composited scrollers.

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 282 matching lines @@
 
   detachScrollbars();
 
   if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
     scrollingCoordinator->willDestroyScrollableArea(this);
 
   // We need to clear the RootFrameViewport's animator since it gets called
   // from non-GC'd objects and RootFrameViewport will still have a pointer to
   // this class.
   if (m_viewportScrollableArea)
-    m_viewportScrollableArea->clearScrollAnimators();
+    m_viewportScrollableArea->clearScrollableArea();
 
-  clearScrollAnimators();
+  clearScrollableArea();
 
   // Destroy |m_autoSizeInfo| as early as possible, to avoid dereferencing
   // partially destroyed |this| via |m_autoSizeInfo->m_frameView|.
   m_autoSizeInfo.clear();
 
   m_postLayoutTasksTimer.stop();
   m_didScrollTimer.stop();
 
   m_renderThrottlingObserverNotificationFactory->cancel();
 
@@ skipping 1148 matching lines @@
 
     if (ScrollingCoordinator* scrollingCoordinator =
             this->scrollingCoordinator())
       scrollingCoordinator->frameViewFixedObjectsDidChange(this);
   }
 }
 
 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
     // to issue the invalidation).  This is because the background fills the
     // main GraphicsLayer, which takes the size of the layout viewport.
     // TODO(skobes): Paint non-fixed backgrounds into the scrolling contents
     // layer and avoid this invalidation (http://crbug.com/568847).
     LayoutViewItem lvi = layoutViewItem();
     if (!lvi.isNull())
       lvi.setShouldDoFullPaintInvalidation();
@@ skipping 900 matching lines @@
 }
 
 bool FrameView::scrollbarsCanBeActive() const {
   if (m_frame->view() != this)
     return false;
 
   return !!m_frame->document();
 }
 
 void FrameView::scrollbarVisibilityChanged() {
+  // Scrollbar enabled state is set from updateScrollbarGeometry.
+  updateScrollbarGeometry();
   LayoutViewItem viewItem = layoutViewItem();
   if (!viewItem.isNull())
     viewItem.clearHitTestCache();
 }
 
 IntRect FrameView::scrollableAreaBoundingBox() const {
   LayoutPartItem ownerLayoutItem = frame().ownerLayoutItem();
   if (ownerLayoutItem.isNull())
     return frameRect();
 
@@ skipping 1193 matching lines @@
 
   return scrollbar->totalSize() - scrollbar->visibleSize();
 }
 
 void FrameView::updateScrollOffset(const ScrollOffset& offset,
                                    ScrollType scrollType) {
   ScrollOffset scrollDelta = offset - m_scrollOffset;
   if (scrollDelta.isZero())
     return;
 
+  showOverlayScrollbars();
+
   if (RuntimeEnabledFeatures::rootLayerScrollingEnabled()) {
     // Don't scroll the FrameView!
     ASSERT_NOT_REACHED();
   }
 
   m_scrollOffset = offset;
 
   if (!scrollbarsSuppressed())
     m_pendingScrollDelta += scrollDelta;
 
@@ skipping 201 matching lines @@
   return m_frame->settings()->ignoreMainFrameOverflowHiddenQuirk() &&
          m_frame->isMainFrame();
 }
 
 void FrameView::updateScrollbarsIfNeeded() {
   if (m_needsScrollbarsUpdate || needsScrollbarReconstruction() ||
       scrollOriginChanged())
     updateScrollbars();
 }
 
-void FrameView::didChangeScrollbarsHidden() {
-  updateScrollbars();
-}
-
 void FrameView::updateScrollbars() {
   m_needsScrollbarsUpdate = false;
 
   if (RuntimeEnabledFeatures::rootLayerScrollingEnabled())
     return;
 
   // Avoid drawing two sets of scrollbars when visual viewport is enabled.
   if (visualViewportSuppliesScrollbars()) {
     m_scrollbarManager.setHasHorizontalScrollbar(false);
     m_scrollbarManager.setHasVerticalScrollbar(false);
@@ skipping 705 matching lines @@
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.width();
 }
 
 int FrameView::initialViewportHeight() const {
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.height();
 }
 
 }  // namespace blink