Don't bother layout until first navigation is done.

third_party/WebKit/Source/web/tests/sim/SimWebViewClient.h

Index: third_party/WebKit/Source/web/tests/sim/SimWebViewClient.h
diff --git a/third_party/WebKit/Source/web/tests/sim/SimWebViewClient.h b/third_party/WebKit/Source/web/tests/sim/SimWebViewClient.h
index e0c1d364b3276ed9f4606c72e6a29f10503ebdca..ce4845b06cdd1ab316a81c35cad7c9e1d3f159ab 100644
--- a/third_party/WebKit/Source/web/tests/sim/SimWebViewClient.h
+++ b/third_party/WebKit/Source/web/tests/sim/SimWebViewClient.h
@@ -16,6 +16,9 @@ public:
     explicit SimWebViewClient(WebLayerTreeView&);
 
     WebLayerTreeView* layerTreeView() override { return m_layerTreeView; }
+    void didUpdateLayout() override { m_hadFirstLayout = true; }
+
+    bool hadFirstLayout() const { return m_hadFirstLayout; }
 
     int visuallyNonEmptyLayoutCount() const { return m_visuallyNonEmptyLayoutCount; }
     int finishedParsingLayoutCount() const { return m_finishedParsingLayoutCount; }
@@ -30,6 +33,7 @@ private:
     int m_finishedLoadingLayoutCount;
 
     WebLayerTreeView* m_layerTreeView;
+    bool m_hadFirstLayout = false;
 };
 
 } // namespace blink