Generalize browser controls adjustment for arbitrary scrollers.

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 155 matching lines @@
           &FrameView::updateWidgetsTimerFired),
       m_isTransparent(false),
       m_baseBackgroundColor(Color::white),
       m_mediaType(MediaTypeNames::screen),
       m_safeToPropagateScrollToParent(true),
       m_scrollCorner(nullptr),
       m_stickyPositionObjectCount(0),
       m_inputEventsScaleFactorForEmulation(1),
       m_layoutSizeFixedToFrameSize(true),
       m_didScrollTimer(this, &FrameView::didScrollTimerFired),
-      m_browserControlsViewportAdjustment(0),
       m_needsUpdateWidgetGeometries(false),
 #if ENABLE(ASSERT)
       m_hasBeenDisposed(false),
 #endif
       m_horizontalScrollbarMode(ScrollbarAuto),
       m_verticalScrollbarMode(ScrollbarAuto),
       m_horizontalScrollbarLock(false),
       m_verticalScrollbarLock(false),
       m_scrollbarsSuppressed(false),
       m_inUpdateScrollbars(false),
@@ skipping 3460 matching lines @@
 
   m_layoutSize = size;
   contentsResized();
 }
 
 void FrameView::didAddScrollbar(Scrollbar& scrollbar,
                                 ScrollbarOrientation orientation) {
   ScrollableArea::didAddScrollbar(scrollbar, orientation);
 }
 
-void FrameView::setBrowserControlsViewportAdjustment(float adjustment) {
-  m_browserControlsViewportAdjustment = adjustment;
-}
-
 PaintLayer* FrameView::layer() const {
   LayoutViewItem layoutView = layoutViewItem();
   if (layoutView.isNull() || !layoutView.compositor())
     return nullptr;
 
   return layoutView.compositor()->rootLayer();
 }
 
 IntSize FrameView::maximumScrollOffsetInt() const {
   // Make the same calculation as in CC's LayerImpl::MaxScrollOffset()
   // FIXME: We probably shouldn't be storing the bounds in a float.
   // crbug.com/422331.
-  IntSize visibleSize =
-      visibleContentSize(ExcludeScrollbars) + browserControlsSize();
+  IntSize visibleSize = visibleContentSize(ExcludeScrollbars);
   IntSize contentBounds = contentsSize();
+
+  FrameHost* host = m_frame->host();
+  DCHECK(host);
+
+  // We need to perform this const_cast since maximumScrollOffsetInt is a const
+  // method but we can't make layoutViewportScrollableArea const since it can
+  // return |this|. Once root-layer-scrolls ships layoutViewportScrollableArea
+  // can be made const.
+  const ScrollableArea* layoutViewport =
+      const_cast<FrameView*>(this)->layoutViewportScrollableArea();
+  TopDocumentRootScrollerController& controller =
+      host->globalRootScrollerController();
+  if (layoutViewport == controller.rootScrollerArea())
+    visibleSize = controller.rootScrollerVisibleArea();
+
   IntSize maximumOffset =
       toIntSize(-scrollOrigin() + (contentBounds - visibleSize));
   return maximumOffset.expandedTo(minimumScrollOffsetInt());
 }
 
 void FrameView::addChild(Widget* child) {
   ASSERT(child != this && !child->parent());
   child->setParent(this);
   m_children.add(child);
 }
@@ skipping 1216 matching lines @@
        reason < MainThreadScrollingReason::kMainThreadScrollingReasonCount;
        ++reason) {
     if (m_mainThreadScrollingReasonsCounter[reason] > 0) {
       reasons |= 1 << reason;
     }
   }
   return reasons;
 }
 
 }  // namespace blink