New TimeToFirstURLJob* navigation metrics now work with PlzNavigate.

content/browser/frame_host/navigator_impl.h

Index: content/browser/frame_host/navigator_impl.h
diff --git a/content/browser/frame_host/navigator_impl.h b/content/browser/frame_host/navigator_impl.h
index c372e7edf90d57a48ca8c03075d9735c8384e8f4..fb54edcf71118a5f79dc154ea3b12566340d6d2b 100644
--- a/content/browser/frame_host/navigator_impl.h
+++ b/content/browser/frame_host/navigator_impl.h
@@ -78,6 +78,7 @@ class CONTENT_EXPORT NavigatorImpl : public Navigator {
                         scoped_ptr<StreamHandle> body) override;
   void LogResourceRequestTime(base::TimeTicks timestamp,
                               const GURL& url) override;
+  void LogAboutToBeginNavigation(base::TimeTicks timestamp) override;
   void LogBeforeUnloadTime(
       const base::TimeTicks& renderer_before_unload_start_time,
       const base::TimeTicks& renderer_before_unload_end_time) override;