Ensure FrameView scrollbars are updated when changing device emulation modes

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 2782 matching lines @@
     return toLocalFrame(parentFrame)->view();
 
   return nullptr;
 }
 
 void FrameView::didChangeGlobalRootScroller() {
   if (!m_frame->settings() || !m_frame->settings()->getViewportEnabled())
     return;
 
   // Avoid drawing two sets of scrollbars when visual viewport is enabled.
+  visualViewportScrollbarsChanged();
+}
+
+// TODO(pdr): This logic is similar to adjustScrollbarExistence and the common
+// logic should be factored into a helper.
+void FrameView::visualViewportScrollbarsChanged() {
   bool hasHorizontalScrollbar = horizontalScrollbar();
   bool hasVerticalScrollbar = verticalScrollbar();
   bool shouldHaveHorizontalScrollbar = false;
   bool shouldHaveVerticalScrollbar = false;
   computeScrollbarExistence(shouldHaveHorizontalScrollbar,
                             shouldHaveVerticalScrollbar, contentsSize());
   m_scrollbarManager.setHasHorizontalScrollbar(shouldHaveHorizontalScrollbar);
   m_scrollbarManager.setHasVerticalScrollbar(shouldHaveVerticalScrollbar);
 
   if (hasHorizontalScrollbar != shouldHaveHorizontalScrollbar ||
-      hasVerticalScrollbar != shouldHaveVerticalScrollbar)
+      hasVerticalScrollbar != shouldHaveVerticalScrollbar) {
     scrollbarExistenceDidChange();
+
+    if (!visualViewportSuppliesScrollbars())
+      updateScrollbarGeometry();
+  }
 }
 
 void FrameView::updateWidgetGeometriesIfNeeded() {
   if (!m_needsUpdateWidgetGeometries)
     return;
 
   m_needsUpdateWidgetGeometries = false;
 
   updateWidgetGeometries();
 }
@@ skipping 2334 matching lines @@
     std::unique_ptr<CompositorAnimationTimeline> timeline) {
   m_animationTimeline = std::move(timeline);
 }
 
 void FrameView::setAnimationHost(
     std::unique_ptr<CompositorAnimationHost> host) {
   m_animationHost = std::move(host);
 }
 
 }  // namespace blink