Re-Compute slow scroll region on frameview visibility change.

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 419d75ec172dbeecae388a6c79699fff76fb6e8e..00a83842a62e217afe1289c0ffd87540892a70d1 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameView.cpp
@@ -418,7 +418,7 @@ void FrameView::setFrameRect(const IntRect& newRect) {
 
   frameRectsChanged();
 
-  updateScrollableAreaSet();
+  updateParentScrollableAreaSet();
 
   if (LayoutViewItem layoutView = this->layoutViewItem()) {
     // TODO(majidvp): It seems that this only needs to be called when size
@@ -540,7 +540,7 @@ void FrameView::setContentsSize(const IntSize& size) {
   if (!page)
     return;
 
-  updateScrollableAreaSet();
+  updateParentScrollableAreaSet();
 
   page->chromeClient().contentsSizeChanged(m_frame.get(), size);
   frame().loader().restoreScrollPositionAndViewState();
@@ -2386,7 +2386,7 @@ FrameView::ScrollingReasons FrameView::getScrollingReasons() {
   return Scrollable;
 }
 
-void FrameView::updateScrollableAreaSet() {
+void FrameView::updateParentScrollableAreaSet() {
   // That ensures that only inner frames are cached.
   FrameView* parentFrameView = this->parentFrameView();
   if (!parentFrameView)
@@ -3337,7 +3337,7 @@ void FrameView::setParent(Widget* parentView) {
 
   Widget::setParent(parentView);
 
-  updateScrollableAreaSet();
+  updateParentScrollableAreaSet();
   setNeedsUpdateViewportIntersection();
 }
 
@@ -4220,11 +4220,17 @@ void FrameView::setParentVisible(bool visible) {
     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);
@@ -4241,8 +4247,9 @@ void FrameView::hide() {
         child->setParentVisible(false);
     }
     setSelfVisible(false);
+    frameViewVisibilityChanged();
     setNeedsCompositingUpdate(layoutViewItem(), CompositingUpdateRebuildTree);
-    updateScrollableAreaSet();
+    updateParentScrollableAreaSet();
   }
 
   Widget::hide();