Add Prerender type to NavigationType for nav timing 2

third_party/WebKit/Source/core/timing/PerformanceNavigationTiming.h

Index: third_party/WebKit/Source/core/timing/PerformanceNavigationTiming.h
diff --git a/third_party/WebKit/Source/core/timing/PerformanceNavigationTiming.h b/third_party/WebKit/Source/core/timing/PerformanceNavigationTiming.h
index 870af370ee1e9cb9c896147f4af8537c40688aef..776af3a21bff62390da5def0576d366eae000be8 100644
--- a/third_party/WebKit/Source/core/timing/PerformanceNavigationTiming.h
+++ b/third_party/WebKit/Source/core/timing/PerformanceNavigationTiming.h
@@ -16,6 +16,13 @@ class CORE_EXPORT PerformanceNavigationTiming final
   DEFINE_WRAPPERTYPEINFO();
 
  public:
+  enum PerformanceNavigationType {
+    KTypeNavigate,
+    KTypeReload,
+    KTypeBackForward,
+    KTypePrerender = 255
+  };
+
   PerformanceNavigationTiming(double timeOrigin,
                               double unloadEventStart,
                               double unloadEventEnd,
@@ -26,7 +33,7 @@ class CORE_EXPORT PerformanceNavigationTiming final
                               double domContentLoadedEventStart,
                               double domContentLoadedEventEnd,
                               double domComplete,
-                              NavigationType,
+                              PerformanceNavigationType,
                               double redirectStart,
                               double redirectEnd,
                               double fetchStart,
@@ -74,7 +81,7 @@ class CORE_EXPORT PerformanceNavigationTiming final
   double m_domContentLoadedEventStart;
   double m_domContentLoadedEventEnd;
   double m_domComplete;
-  NavigationType m_type;
+  PerformanceNavigationType m_type;
   double m_redirectStart;
   double m_redirectEnd;
   double m_fetchStart;