Adds scroll position/scale emulation to DevTools.

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

Index: third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp b/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
index b44a02ca9f61dc2195393455c3dee721d9b18933..0a8af6fca6bb4fb7e09de15f16b6c1ead882e0d6 100644
--- a/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
@@ -596,11 +596,11 @@ void PaintLayerCompositor::frameViewDidScroll()
         scrollingCoordinatorHandlesOffset = scrollingCoordinator->scrollableAreaScrollLayerDidChange(frameView);
     }
 
-    // Scroll position = scroll minimum + scroll offset. Adjust the layer's
+    // Scroll position = scroll origin + scroll offset. Adjust the layer's
     // position to handle whatever the scroll coordinator isn't handling.
-    // The minimum scroll position is non-zero for RTL pages with overflow.
+    // The scroll origin is non-zero for RTL pages with overflow.
     if (scrollingCoordinatorHandlesOffset)
-        m_scrollLayer->setPosition(-frameView->minimumScrollPosition());
+        m_scrollLayer->setPosition(frameView->scrollOrigin());
     else
         m_scrollLayer->setPosition(-scrollPosition);