Adds DevTools commands for forced viewport override.

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

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ skipping 172 matching lines @@
     void adjustViewSizeAndLayout();
 
     // Scale used to convert incoming input events.
     float inputEventsScaleFactor() const;
 
     // Offset used to convert incoming input events while emulating device metics.
     IntSize inputEventsOffsetForEmulation() const;
     void setInputEventsTransformForEmulation(const IntSize&, float);
 
     void setScrollPosition(const DoublePoint&, ScrollType, ScrollBehavior = ScrollBehaviorInstant) override;
+    void didChangeScrollOffset();
 
     void didUpdateElasticOverscroll();
 
     void viewportSizeChanged(bool widthChanged, bool heightChanged);
 
     AtomicString mediaType() const;
     void setMediaType(const AtomicString&);
     void adjustMediaTypeForPrinting(bool printing);
 
     WebDisplayMode displayMode() { return m_displayMode; }
@@ skipping 238 matching lines @@
 
     bool canHaveScrollbars() const { return horizontalScrollbarMode() != ScrollbarAlwaysOff || verticalScrollbarMode() != ScrollbarAlwaysOff; }
 
     // The visible content rect has a location that is the scrolled offset of
     // the document. The width and height are the layout viewport width and
     // height. By default the scrollbars themselves are excluded from this
     // rectangle, but an optional boolean argument allows them to be included.
     IntRect visibleContentRect(IncludeScrollbarsInRect = ExcludeScrollbars) const override;
     IntSize visibleContentSize(IncludeScrollbarsInRect = ExcludeScrollbars) const;
 
+    // Set a custom painting area. Used for visual transform overrides to ensure
+    // that the content inside the overridden visible area is painted. If not
+    // set, the painting area defaults to visibleContentRect().
+    void setVisibleContentRectForPainting(const IntRect&);
+    void resetVisibleContentRectForPainting();
+    IntRect visibleContentRectForPainting() const;
+
     // Functions for getting/setting the size of the document contained inside the FrameView (as an IntSize or as individual width and height
     // values).
     IntSize contentsSize() const override; // Always at least as big as the visibleWidth()/visibleHeight().
     int contentsWidth() const { return contentsSize().width(); }
     int contentsHeight() const { return contentsSize().height(); }
 
     // Functions for querying the current scrolled position (both as a point, a size, or as individual X and Y values).
     // Be careful in using the Double version scrollPositionDouble() and scrollOffsetDouble(). They are meant to be
     // used to communicate the fractional scroll position/offset with chromium compositor which can do sub-pixel positioning.
     // Do not call these if the scroll position/offset is used in Blink for positioning. Use the Int version instead.
@@ skipping 406 matching lines @@
     ScrollbarMode m_verticalScrollbarMode;
 
     bool m_horizontalScrollbarLock;
     bool m_verticalScrollbarLock;
 
     ChildrenWidgetSet m_children;
 
     DoubleSize m_pendingScrollDelta;
     DoublePoint m_scrollPosition;
     IntSize m_contentsSize;
+    std::unique_ptr<IntRect> m_visibleContentRectForPainting;

[Sami, 2016/08/11 13:24:24]

Could this be a WTF::Optional?

[Eric Seckler, 2016/08/11 15:12:38]

Indeed :)

 
     int m_scrollbarsAvoidingResizer;
     bool m_scrollbarsSuppressed;
 
     bool m_inUpdateScrollbars;
 
     std::unique_ptr<LayoutAnalyzer> m_analyzer;
 
     // Mark if something has changed in the mapping from Frame to GraphicsLayer
     // and the Frame Timing regions should be recalculated.
@@ skipping 71 matching lines @@
     if (m_visuallyNonEmptyPixelCount > visualPixelThreshold)
         setIsVisuallyNonEmpty();
 }
 
 DEFINE_TYPE_CASTS(FrameView, Widget, widget, widget->isFrameView(), widget.isFrameView());
 DEFINE_TYPE_CASTS(FrameView, ScrollableArea, scrollableArea, scrollableArea->isFrameView(), scrollableArea.isFrameView());
 
 } // namespace blink
 
 #endif // FrameView_h