Don't use ScrollbarAlwaysOff for hide_scrollbars.

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 3320 matching lines @@
 
 void FrameView::addChild(Widget* child)
 {
     ASSERT(child != this && !child->parent());
     child->setParent(this);
     m_children.add(child);
 }
 
 void FrameView::setHasHorizontalScrollbar(bool hasBar)
 {
+    DCHECK(m_frame->settings());
+    if (m_frame->settings()->hideScrollbars())
+        hasBar = false;
+
     if (hasBar == !!m_horizontalScrollbar)
         return;
 
     if (hasBar) {
         m_horizontalScrollbar = createScrollbar(HorizontalScrollbar);
         addChild(m_horizontalScrollbar.get());
         didAddScrollbar(*m_horizontalScrollbar, HorizontalScrollbar);
         m_horizontalScrollbar->styleChanged();
     } else {
         willRemoveScrollbar(*m_horizontalScrollbar, HorizontalScrollbar);
         // If the scrollbar has been marked as overlapping the window resizer,
         // then its removal should reduce the count.
         if (m_horizontalScrollbar->overlapsResizer())
             adjustScrollbarsAvoidingResizerCount(-1);
         removeChild(m_horizontalScrollbar.get());
         m_horizontalScrollbar->disconnectFromScrollableArea();
         m_horizontalScrollbar = nullptr;
     }
 
     setScrollCornerNeedsPaintInvalidation();
 }
 
 void FrameView::setHasVerticalScrollbar(bool hasBar)
 {
+    DCHECK(m_frame->settings());
+    if (m_frame->settings()->hideScrollbars())
+        hasBar = false;
+
     if (hasBar == !!m_verticalScrollbar)
         return;
 
     if (hasBar) {
         m_verticalScrollbar = createScrollbar(VerticalScrollbar);
         addChild(m_verticalScrollbar.get());
         didAddScrollbar(*m_verticalScrollbar, VerticalScrollbar);
         m_verticalScrollbar->styleChanged();
     } else {
         willRemoveScrollbar(*m_verticalScrollbar, VerticalScrollbar);
@@ skipping 17 matching lines @@
     // If the page's overflow setting has disabled scrolling, do not allow anything to override that setting.
     // http://crbug.com/426447
     LayoutObject* viewport = viewportLayoutObject();
     if (viewport && !shouldIgnoreOverflowHidden()) {
         if (viewport->style()->overflowX() == OverflowHidden)
             horizontalMode = ScrollbarAlwaysOff;
         if (viewport->style()->overflowY() == OverflowHidden)
             verticalMode = ScrollbarAlwaysOff;
     }
 
-    DCHECK(m_frame->settings());
-    if (m_frame->settings()->hideScrollbars()) {
-        horizontalMode = ScrollbarAlwaysOff;
-        verticalMode = ScrollbarAlwaysOff;
-    }
-
     if (horizontalMode != horizontalScrollbarMode() && !m_horizontalScrollbarLock) {
         m_horizontalScrollbarMode = horizontalMode;
         needsUpdate = true;
     }
 
     if (verticalMode != verticalScrollbarMode() && !m_verticalScrollbarLock) {
         m_verticalScrollbarMode = verticalMode;
         needsUpdate = true;
     }
 
@@ skipping 1001 matching lines @@
 }
 
 bool FrameView::canThrottleRendering() const
 {
     if (!RuntimeEnabledFeatures::renderingPipelineThrottlingEnabled())
         return false;
     return m_subtreeThrottled || (m_hiddenForThrottling && m_crossOriginForThrottling);
 }
 
 } // namespace blink