Adds DevTools commands for forced viewport override.

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp

Index: third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
index 68195ca6945f7ab995c9e90e31483c5c4f7f5c71..aef2d23fab276d26ceda751801a63870f5d50bca 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
@@ -2274,6 +2274,8 @@ static void paintScrollbar(const Scrollbar* scrollbar, GraphicsContext& context,
     scrollbar->paint(context, CullRect(transformedClip));
 }
 
+// TODO(eseckler): Make recording distance configurable, e.g. for use in
+// headless, where we would like to record an exact area (distance = 0).
 static const int kPixelDistanceToRecord = 4000;
 
 IntRect CompositedLayerMapping::recomputeInterestRect(const GraphicsLayer* graphicsLayer) const
@@ -2309,7 +2311,7 @@ IntRect CompositedLayerMapping::recomputeInterestRect(const GraphicsLayer* graph
     while (rootView->frame()->ownerLayoutObject())
         rootView = rootView->frame()->ownerLayoutObject()->view();
     anchorLayoutObject->mapToVisualRectInAncestorSpace(rootView, visibleContentRect);
-    visibleContentRect.intersect(LayoutRect(rootView->frameView()->visibleContentRect()));
+    visibleContentRect.intersect(LayoutRect(rootView->frameView()->visibleContentRectForRecording()));
 
     IntRect enclosingGraphicsLayerBounds(enclosingIntRect(graphicsLayerBounds));