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 5cfb85f3f5f5fddc20055ed245de877eeb10987f..f189dc813d7d5e61398b0fdb35359217102be856 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
@@ -539,7 +539,7 @@ void FrameView::setContentsSize(const IntSize& size) {
   if (!page)
     return;
 
-  updateScrollableAreaSet();
+  updateParentScrollableAreaSet();
 
   page->chromeClient().contentsSizeChanged(m_frame.get(), size);
   frame().loader().restoreScrollPositionAndViewState();
@@ -2384,7 +2384,7 @@ 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)
@@ -3340,7 +3340,7 @@ void FrameView::setParent(Widget* parentView) {
 
   Widget::setParent(parentView);
 
-  updateScrollableAreaSet();
+  updateParentScrollableAreaSet();
   setNeedsUpdateViewportIntersection();
 }
 
@@ -4226,8 +4226,11 @@ void FrameView::setParentVisible(bool visible) {
 void FrameView::show() {
   if (!isSelfVisible()) {
     setSelfVisible(true);
+    if (ScrollingCoordinator* scrollingCoordinator =
+            this->scrollingCoordinator())
+      scrollingCoordinator->frameViewVisibilityDidChange();
     setNeedsCompositingUpdate(layoutViewItem(), CompositingUpdateRebuildTree);
-    updateScrollableAreaSet();
+    updateParentScrollableAreaSet();
     if (isParentVisible()) {
       for (const auto& child : m_children)
         child->setParentVisible(true);
@@ -4244,8 +4247,11 @@ void FrameView::hide() {
         child->setParentVisible(false);
     }
     setSelfVisible(false);
+    if (ScrollingCoordinator* scrollingCoordinator =
+            this->scrollingCoordinator())
+      scrollingCoordinator->frameViewVisibilityDidChange();
     setNeedsCompositingUpdate(layoutViewItem(), CompositingUpdateRebuildTree);
-    updateScrollableAreaSet();
+    updateParentScrollableAreaSet();
   }
 
   Widget::hide();