Re-Compute slow scroll region on frameview visibility change.

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 400 matching lines @@
 
   m_needsScrollbarsUpdate = frameSizeChanged;
   // TODO(wjmaclean): find out why scrollbars fail to resize for complex
   // subframes after changing the zoom level. For now always calling
   // updateScrollbarsIfNeeded() here fixes the issue, but it would be good to
   // discover the deeper cause of this. http://crbug.com/607987.
   updateScrollbarsIfNeeded();
 
   frameRectsChanged();
 
-  updateScrollableAreaSet();
+  updateParentScrollableAreaSet();
 
   if (LayoutViewItem layoutView = this->layoutViewItem()) {
     // TODO(majidvp): It seems that this only needs to be called when size
     // is updated ignoring any change in the location.
     if (layoutView.usesCompositing())
       layoutView.compositor()->frameViewDidChangeSize();
   }
 
   if (frameSizeChanged) {
     viewportSizeChanged(newRect.width() != oldRect.width(),
@@ skipping 101 matching lines @@
     return;
 
   m_contentsSize = size;
   updateScrollbars();
   ScrollableArea::contentsResized();
 
   Page* page = frame().page();
   if (!page)
     return;
 
-  updateScrollableAreaSet();
+  updateParentScrollableAreaSet();
 
   page->chromeClient().contentsSizeChanged(m_frame.get(), size);
   frame().loader().restoreScrollPositionAndViewState();
 }
 
 void FrameView::adjustViewSize() {
   if (m_suppressAdjustViewSize)
     return;
 
   LayoutViewItem layoutViewItem = this->layoutViewItem();
@@ skipping 1825 matching lines @@
   ScrollbarMode verticalMode;
   calculateScrollbarModes(horizontalMode, verticalMode,
                           RulesFromWebContentOnly);
   if (horizontalMode == ScrollbarAlwaysOff &&
       verticalMode == ScrollbarAlwaysOff)
     return NotScrollableExplicitlyDisabled;
 
   return Scrollable;
 }
 
-void FrameView::updateScrollableAreaSet() {
+void FrameView::updateParentScrollableAreaSet() {
   // That ensures that only inner frames are cached.
   FrameView* parentFrameView = this->parentFrameView();
   if (!parentFrameView)
     return;
 
   if (!isScrollable()) {
     parentFrameView->removeScrollableArea(this);
     return;
   }
 
@@ skipping 930 matching lines @@
     return;
   m_animatingScrollableAreas->remove(scrollableArea);
 }
 
 void FrameView::setParent(Widget* parentView) {
   if (parentView == parent())
     return;
 
   Widget::setParent(parentView);
 
-  updateScrollableAreaSet();
+  updateParentScrollableAreaSet();
   setNeedsUpdateViewportIntersection();
 }
 
 void FrameView::removeChild(Widget* child) {
   ASSERT(child->parent() == this);
 
   if (child->isFrameView())
     removeScrollableArea(toFrameView(child));
 
   child->setParent(0);
@@ skipping 862 matching lines @@
 
   Widget::setParentVisible(visible);
 
   if (!isSelfVisible())
     return;
 
   for (const auto& child : m_children)
     child->setParentVisible(visible);
 }
 
+void FrameView::frameViewVisibilityChanged() {

[majidvp, 2016/11/02 14:15:17]

This function seems superfulous. It is reducing one very
simple line. I would get rid of it.

[MuVen, 2016/11/02 17:07:47]

Done.

+  if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
+    scrollingCoordinator->frameViewVisibilityDidChange();
+}
+
 void FrameView::show() {
   if (!isSelfVisible()) {
     setSelfVisible(true);
+    frameViewVisibilityChanged();
     setNeedsCompositingUpdate(layoutViewItem(), CompositingUpdateRebuildTree);
-    updateScrollableAreaSet();
+    updateParentScrollableAreaSet();
     if (isParentVisible()) {
       for (const auto& child : m_children)
         child->setParentVisible(true);
     }
   }
 
   Widget::show();
 }
 
 void FrameView::hide() {
   if (isSelfVisible()) {
     if (isParentVisible()) {
       for (const auto& child : m_children)
         child->setParentVisible(false);
     }
     setSelfVisible(false);
+    frameViewVisibilityChanged();
     setNeedsCompositingUpdate(layoutViewItem(), CompositingUpdateRebuildTree);
-    updateScrollableAreaSet();
+    updateParentScrollableAreaSet();
   }
 
   Widget::hide();
 }
 
 int FrameView::viewportWidth() const {
   int viewportWidth = layoutSize(IncludeScrollbars).width();
   return adjustForAbsoluteZoom(viewportWidth, layoutView());
 }
 
@@ skipping 233 matching lines @@
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.width();
 }
 
 int FrameView::initialViewportHeight() const {
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.height();
 }
 
 }  // namespace blink