Add Prerender type to NavigationType for nav timing 2

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

Index: third_party/WebKit/Source/core/timing/PerformanceNavigationTiming.cpp
diff --git a/third_party/WebKit/Source/core/timing/PerformanceNavigationTiming.cpp b/third_party/WebKit/Source/core/timing/PerformanceNavigationTiming.cpp
index 080836e01b62a151347b338d2609ebba07393c95..b61a635a177790d3e1a52caa3ed9a55ff7990c9f 100644
--- a/third_party/WebKit/Source/core/timing/PerformanceNavigationTiming.cpp
+++ b/third_party/WebKit/Source/core/timing/PerformanceNavigationTiming.cpp
@@ -121,16 +121,18 @@ double PerformanceNavigationTiming::loadEventEnd() const {
 }
 
 AtomicString PerformanceNavigationTiming::type() const {
-  // TODO(sunjian) Right now NavigationType doesn't seem to have a Prerender
-  // type yet, need to look into this crbug/663217
   switch (m_type) {
-    case NavigationTypeReload:
+    case NavigationType::Reload:
       return "reload";
-    case NavigationTypeBackForward:
+    case NavigationType::BackForward:
       return "back_forward";
-    default:
+    case NavigationType::Prerender:
+      return "prerender";
+    case NavigationType::Navigate:
       return "navigate";
   }
+  NOTREACHED();
+  return "navigate";
 }
 
 unsigned short PerformanceNavigationTiming::redirectCount() const {