Set attached flag before we call didAddScrollbar

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 afe9dd5c7b72edbb52f6071269e38f015d9b2e6a..66f01b8733e6e900ce04f19451113bda96fc6287 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameView.cpp
@@ -395,9 +395,9 @@ void FrameView::ScrollbarManager::setHasHorizontalScrollbar(bool hasScrollbar) {
   if (hasScrollbar) {
     m_hBar = createScrollbar(HorizontalScrollbar);
     m_scrollableArea->layoutBox()->document().view()->addChild(m_hBar.get());
+    m_hBarIsAttached = 1;
     m_scrollableArea->didAddScrollbar(*m_hBar, HorizontalScrollbar);
     m_hBar->styleChanged();
-    m_hBarIsAttached = 1;
   } else {
     m_hBarIsAttached = 0;
     destroyScrollbar(HorizontalScrollbar);
@@ -413,9 +413,9 @@ void FrameView::ScrollbarManager::setHasVerticalScrollbar(bool hasScrollbar) {
   if (hasScrollbar) {
     m_vBar = createScrollbar(VerticalScrollbar);
     m_scrollableArea->layoutBox()->document().view()->addChild(m_vBar.get());
+    m_vBarIsAttached = 1;
     m_scrollableArea->didAddScrollbar(*m_vBar, VerticalScrollbar);
     m_vBar->styleChanged();
-    m_vBarIsAttached = 1;
   } else {
     m_vBarIsAttached = 0;
     destroyScrollbar(VerticalScrollbar);