Replace pinch scrollbars with regular scrollbars.

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 658 matching lines @@
 bool FrameView::usesCompositedScrolling() const
 {
     LayoutView* layoutView = this->layoutView();
     if (!layoutView)
         return false;
     if (m_frame->settings() && m_frame->settings()->preferCompositingToLCDTextEnabled())
         return layoutView->compositor()->inCompositingMode();
     return false;
 }
 
+GraphicsLayer* FrameView::layerForScrollbarContainer() const

[skobes, 2015/08/25 00:19:01]

Do we need a similar override in DeprecatedPaintLayerScrollableArea when
--root-layer-scrolls is enabled?

[aelias_OOO_until_Jul13, 2015/08/25 02:50:27]

Done, and I also fixed the layer attachment with that flag.

+{
+    if (m_frame->isMainFrame())
+        return page()->frameHost().visualViewport().layerForScrollbarContainer();
+    return layerForContainer();
+}
+
 GraphicsLayer* FrameView::layerForScrolling() const
 {
     LayoutView* layoutView = this->layoutView();
     if (!layoutView)
         return nullptr;
     return layoutView->compositor()->frameScrollLayer();
 }
 
 GraphicsLayer* FrameView::layerForHorizontalScrollbar() const
 {
@@ skipping 2261 matching lines @@
 
 bool FrameView::isFlippedDocument() const
 {
     LayoutView* layoutView = this->layoutView();
     if (!layoutView)
         return false;
 
     return layoutView->hasFlippedBlocksWritingMode();
 }
 
-bool FrameView::visualViewportSuppliesScrollbars() const
-{
-    return m_frame->isMainFrame() && m_frame->settings() && m_frame->settings()->viewportMetaEnabled();
-}
-
 AXObjectCache* FrameView::axObjectCache() const
 {
     if (frame().document())
         return frame().document()->existingAXObjectCache();
     return nullptr;
 }
 
 void FrameView::setCursor(const Cursor& cursor)
 {
     Page* page = frame().page();
@@ skipping 227 matching lines @@
     scrollTo(clampScrollPosition(offset));
 }
 
 void FrameView::windowResizerRectChanged()
 {
     updateScrollbars(scrollOffsetDouble());
 }
 
 bool FrameView::hasOverlayScrollbars() const
 {
-
     return (m_horizontalScrollbar && m_horizontalScrollbar->isOverlayScrollbar())
         || (m_verticalScrollbar && m_verticalScrollbar->isOverlayScrollbar());
 }
 
 void FrameView::computeScrollbarExistence(bool& newHasHorizontalScrollbar, bool& newHasVerticalScrollbar, const IntSize& docSize, ComputeScrollbarExistenceOption option) const
 {
     bool hasHorizontalScrollbar = m_horizontalScrollbar;
     bool hasVerticalScrollbar = m_verticalScrollbar;
 
     newHasHorizontalScrollbar = hasHorizontalScrollbar;
@@ skipping 11 matching lines @@
         newHasVerticalScrollbar = (vScroll == ScrollbarAlwaysOn);
 
     if (m_scrollbarsSuppressed || (hScroll != ScrollbarAuto && vScroll != ScrollbarAuto))
         return;
 
     if (hScroll == ScrollbarAuto)
         newHasHorizontalScrollbar = docSize.width() > visibleWidth();
     if (vScroll == ScrollbarAuto)
         newHasVerticalScrollbar = docSize.height() > visibleHeight();
 
-    if (hasOverlayScrollbars())
+    if (hasOverlayScrollbars()) {
+        if (m_frame->isMainFrame())
+            newHasHorizontalScrollbar = newHasVerticalScrollbar = true;

[skobes, 2015/08/25 00:19:01]

Why is this needed?

[aelias_OOO_until_Jul13, 2015/08/25 02:50:27]

So that scrollbars are shown when zooming in (particularly on Android), even if
they weren't needed at minimum scale.  Note that CC is smart about hiding a
scrollbar if that orientation is nonscrollable.

[aelias_OOO_until_Jul13, 2015/08/26 04:47:48]

Unfortunately, this approach turned out to be flaky (and broken in a different
way when --root-layer-scrolls), so I deleted this line and ended up bringing
back the VisualViewport scrollbars, which are now Android-only scrollbars.  The
VisualViewport scrollbar deletion should be more feasible when
--root-layer-scrolls is shipped.

         return;
+    }
 
     IntSize fullVisibleSize = visibleContentRect(IncludeScrollbars).size();
 
     bool attemptToRemoveScrollbars = (option == FirstPass
         && docSize.width() <= fullVisibleSize.width() && docSize.height() <= fullVisibleSize.height());
     if (attemptToRemoveScrollbars) {
         if (hScroll == ScrollbarAuto)
             newHasHorizontalScrollbar = false;
         if (vScroll == ScrollbarAuto)
             newHasVerticalScrollbar = false;
@@ skipping 120 matching lines @@
     return hasAnyScrollbar && (shouldUseCustom != hasCustom);
 }
 
 bool FrameView::shouldIgnoreOverflowHidden() const
 {
     return m_frame->settings()->ignoreMainFrameOverflowHiddenQuirk() && m_frame->isMainFrame();
 }
 
 void FrameView::updateScrollbars(const DoubleSize& desiredOffset)
 {
-    // Avoid drawing two sets of scrollbars when visual viewport is enabled.
-    if (visualViewportSuppliesScrollbars()) {
-        setHasHorizontalScrollbar(false);
-        setHasVerticalScrollbar(false);
-        setScrollOffsetFromUpdateScrollbars(desiredOffset);
-        return;
-    }
-
     if (m_inUpdateScrollbars)
         return;
     InUpdateScrollbarsScope inUpdateScrollbarsScope(this);
 
     IntSize oldVisibleSize = visibleContentSize();
 
     bool scrollbarExistenceChanged = false;
 
     if (needsScrollbarReconstruction()) {
         setHasHorizontalScrollbar(false);
@@ skipping 565 matching lines @@
 
     if (!graphicsLayer)
         return;
 
     DeprecatedPaintLayer::mapRectToPaintInvalidationBacking(localFrame->contentLayoutObject(), paintInvalidationContainer, viewRect);
 
     graphicsLayerTimingRequests.add(graphicsLayer, Vector<std::pair<int64_t, WebRect>>()).storedValue->value.append(std::make_pair(m_frame->frameID(), enclosingIntRect(viewRect)));
 }
 
 } // namespace blink