Attempt scroll restoration anytime viewport size changes

Source/core/loader/FrameLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008 Alp Toker <alp@atoker.com>
  * Copyright (C) Research In Motion Limited 2009. All rights reserved.
  * Copyright (C) 2011 Kris Jordan <krisjordan@gmail.com>
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ skipping 1096 matching lines @@
 }
 
 FrameLoadType FrameLoader::loadType() const
 {
     return m_loadType;
 }
 
 void FrameLoader::restoreScrollPositionAndViewState()
 {
     FrameView* view = m_frame->view();
-    if (!m_frame->page() || !view || !m_currentItem || !m_stateMachine.committedFirstRealDocumentLoad())
+    if (!m_frame->page() || !view || !view->layoutViewportScrollableArea() || !m_currentItem || !m_stateMachine.committedFirstRealDocumentLoad())
         return;
 
     if (!needsHistoryItemRestore(m_loadType))
         return;
 
     bool shouldRestoreScroll = m_currentItem->scrollRestorationType() != ScrollRestorationManual;
     bool shouldRestoreScale = m_currentItem->pageScaleFactor();
 
     // This tries to balance:
     //   1. restoring as soon as possible
     //   2. not overriding user scroll (TODO(majidvp): also respect user scale)
     //   3. detecting clamping to avoid repeatedly popping the scroll position
     //      down as the page height increases
     //   4. ignore clamp detection if we are not restoring scroll or after load
     //      completes because that may be because the page will never reach its
     //      previous height
-    bool canRestoreWithoutClamping = view->clampOffsetAtScale(m_currentItem->scrollPoint(), 1) == m_currentItem->scrollPoint();
+    bool canRestoreWithoutClamping = view->layoutViewportScrollableArea()->clampScrollPosition(m_currentItem->scrollPoint()) == m_currentItem->scrollPoint();
     bool canRestoreWithoutAnnoyingUser = !documentLoader()->initialScrollState().wasScrolledByUser
         && (canRestoreWithoutClamping || !m_frame->isLoading() || !shouldRestoreScroll);
     if (!canRestoreWithoutAnnoyingUser)
         return;
 
     if (shouldRestoreScroll)
         view->layoutViewportScrollableArea()->setScrollPosition(m_currentItem->scrollPoint(), ProgrammaticScroll);
 
     // For main frame restore scale and visual viewport position
     if (m_frame->isMainFrame()) {
@@ skipping 371 matching lines @@
     // FIXME: We need a way to propagate insecure requests policy flags to
     // out-of-process frames. For now, we'll always use default behavior.
     if (!parentFrame->isLocalFrame())
         return nullptr;
 
     ASSERT(toLocalFrame(parentFrame)->document());
     return toLocalFrame(parentFrame)->document()->insecureNavigationsToUpgrade();
 }
 
 } // namespace blink