Revert of Remove invert viewport scroll order setting from Blink

third_party/WebKit/Source/core/frame/RootFrameViewport.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef RootFrameViewport_h
 #define RootFrameViewport_h
 
 #include "core/CoreExport.h"
 #include "platform/scroll/ScrollableArea.h"
 
 namespace blink {
 
 class LayoutRect;
 
 // ScrollableArea for the root frame's viewport. This class ties together the
 // concepts of layout and visual viewports, used in pinch-to-zoom. This class
 // takes two ScrollableAreas, one for the visual viewport and one for the
 // layout viewport, and delegates and composes the ScrollableArea API as needed
 // between them. For most scrolling APIs, this class will split the scroll up
 // between the two viewports in accord with the pinch-zoom semantics. For other
 // APIs that don't make sense on the combined viewport, the call is delegated to
 // the layout viewport. Thus, we could say this class is a decorator on the
 // FrameView scrollable area that adds pinch-zoom semantics to scrolling.
 class CORE_EXPORT RootFrameViewport final : public NoBaseWillBeGarbageCollectedFinalized<RootFrameViewport>, public ScrollableArea {
     USING_FAST_MALLOC_WILL_BE_REMOVED(RootFrameViewport);
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(RootFrameViewport);
 public:
-    static PassOwnPtrWillBeRawPtr<RootFrameViewport> create(ScrollableArea& visualViewport, ScrollableArea& layoutViewport)
+    static PassOwnPtrWillBeRawPtr<RootFrameViewport> create(ScrollableArea& visualViewport, ScrollableArea& layoutViewport, bool invertScrollOrder = false)
     {
-        return adoptPtrWillBeNoop(new RootFrameViewport(visualViewport, layoutViewport));
+        return adoptPtrWillBeNoop(new RootFrameViewport(visualViewport, layoutViewport, invertScrollOrder));
     }
 
     DECLARE_VIRTUAL_TRACE();
 
     // ScrollableArea Implementation
     void setScrollPosition(const DoublePoint&, ScrollType, ScrollBehavior = ScrollBehaviorInstant) override;
     LayoutRect scrollIntoView(
         const LayoutRect& rectInContent,
         const ScrollAlignment& alignX,
         const ScrollAlignment& alignY,
@@ skipping 23 matching lines @@
     GraphicsLayer* layerForHorizontalScrollbar() const override;
     GraphicsLayer* layerForVerticalScrollbar() const override;
     ScrollResultOneDimensional userScroll(ScrollDirectionPhysical, ScrollGranularity, float delta = 1) override;
     bool scrollAnimatorEnabled() const override;
     HostWindow* hostWindow() const override;
     void serviceScrollAnimations(double) override;
     void updateCompositorScrollAnimations() override;
     ScrollBehavior scrollBehaviorStyle() const override;
 
 private:
-    RootFrameViewport(ScrollableArea& visualViewport, ScrollableArea& layoutViewport);
+    RootFrameViewport(ScrollableArea& visualViewport, ScrollableArea& layoutViewport, bool invertScrollOrder);
 
     DoublePoint scrollOffsetFromScrollAnimators() const;
 
     void distributeScrollBetweenViewports(const DoublePoint&, ScrollType, ScrollBehavior);
 
     // If either of the layout or visual viewports are scrolled explicitly (i.e. not
     // through this class), their updated offset will not be reflected in this class'
     // animator so use this method to pull updated values when necessary.
     void updateScrollAnimator();
 
     ScrollableArea& visualViewport() const { ASSERT(m_visualViewport); return *m_visualViewport; }
     ScrollableArea& layoutViewport() const { ASSERT(m_layoutViewport); return *m_layoutViewport; }
 
     RawPtrWillBeMember<ScrollableArea> m_visualViewport;
     RawPtrWillBeMember<ScrollableArea> m_layoutViewport;
+
+    // Experimental flag. If the experiment is enabled, scroll the visual viewport first,
+    // the bubble scrolls to the layout viewport.
+    bool m_invertScrollOrder;
 };
 
 } // namespace blink
 
 #endif // RootFrameViewport_h