Adds DevTools commands for forced viewport override.

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 3291 matching lines @@
 IntRect FrameView::visibleContentRect(IncludeScrollbarsInRect scrollbarInclusion) const
 {
     return IntRect(flooredIntPoint(m_scrollPosition), visibleContentSize(scrollbarInclusion));
 }
 
 IntSize FrameView::contentsSize() const
 {
     return m_contentsSize;
 }
 
+IntRect FrameView::visibleContentRectForPainting() const
+{
+    if (m_visibleContentRectForPainting)
+        return *m_visibleContentRectForPainting;
+    return visibleContentRect();
+}
+
+void FrameView::setVisibleContentRectForPainting(const IntRect& rect)
+{
+    m_visibleContentRectForPainting = IntRect(rect);
+}
+
+void FrameView::resetVisibleContentRectForPainting()
+{
+    m_visibleContentRectForPainting = WTF::nullopt;
+}
+
 IntPoint FrameView::minimumScrollPosition() const
 {
     return IntPoint(-scrollOrigin().x(), -scrollOrigin().y());
 }
 
 void FrameView::adjustScrollbarOpacity()
 {
     if (m_horizontalScrollbar && layerForHorizontalScrollbar()) {
         bool isOpaqueScrollbar = !m_horizontalScrollbar->isOverlayScrollbar();
         layerForHorizontalScrollbar()->setContentsOpaque(isOpaqueScrollbar);
@@ skipping 58 matching lines @@
     }
 
     if (m_didScrollTimer.isActive())
         m_didScrollTimer.stop();
     m_didScrollTimer.startOneShot(resourcePriorityUpdateDelayAfterScroll, BLINK_FROM_HERE);
 
     if (AXObjectCache* cache = m_frame->document()->existingAXObjectCache())
         cache->handleScrollPositionChanged(this);
 
     frame().loader().saveScrollState();
-    frame().loader().client()->didChangeScrollOffset();
+    didChangeScrollOffset();
 
     if (scrollType == CompositorScroll && m_frame->isMainFrame()) {
         if (DocumentLoader* documentLoader = m_frame->loader().documentLoader())
             documentLoader->initialScrollState().wasScrolledByUser = true;
     }
 
     if (scrollType != AnchoringScroll)
         clearScrollAnchor();
 }
 
+void FrameView::didChangeScrollOffset()
+{
+    frame().loader().client()->didChangeScrollOffset();
+    if (frame().isMainFrame())
+        frame().host()->chromeClient().mainFrameScrollOffsetChanged();
+}
+
 void FrameView::clearScrollAnchor()
 {
     if (!RuntimeEnabledFeatures::scrollAnchoringEnabled())
         return;
     m_scrollAnchor.clear();
 }
 
 void FrameView::windowResizerRectChanged()
 {
     updateScrollbars();
@@ skipping 836 matching lines @@
 }
 
 bool FrameView::canThrottleRendering() const
 {
     if (!RuntimeEnabledFeatures::renderingPipelineThrottlingEnabled())
         return false;
     return m_subtreeThrottled || (m_hiddenForThrottling && m_crossOriginForThrottling);
 }
 
 } // namespace blink