Avoid element id collisions with the visual viewport

third_party/WebKit/Source/core/frame/VisualViewport.cpp

Index: third_party/WebKit/Source/core/frame/VisualViewport.cpp
diff --git a/third_party/WebKit/Source/core/frame/VisualViewport.cpp b/third_party/WebKit/Source/core/frame/VisualViewport.cpp
index 61572c8f2ff53a1aec04dea03dc4032b8cd09927..c75ad1e66edb10b4ce1ead1bd5a75bc752191696 100644
--- a/third_party/WebKit/Source/core/frame/VisualViewport.cpp
+++ b/third_party/WebKit/Source/core/frame/VisualViewport.cpp
@@ -391,9 +391,10 @@ void VisualViewport::attachToLayerTree(GraphicsLayer* currentLayerTreeRoot) {
         m_innerViewportContainerLayer->platformLayer());
     m_innerViewportScrollLayer->platformLayer()->setUserScrollable(true, true);
     if (mainFrame()) {
-      if (Document* document = mainFrame()->document())
+      if (Document* document = mainFrame()->document()) {
         m_innerViewportScrollLayer->setElementId(createCompositorElementId(
-            DOMNodeIds::idForNode(document), CompositorSubElementId::Scroll));
+            DOMNodeIds::idForNode(document), CompositorSubElementId::Viewport));
+      }
     }
 
     m_rootTransformLayer->addChild(m_innerViewportContainerLayer.get());