Add Prerender type to NavigationType for nav timing 2

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

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 31 matching lines @@
 class DocumentLoadTiming;
 class DocumentLoader;
 class DocumentParserTiming;
 class DocumentTiming;
 class LocalFrame;
 class PaintTiming;
 class ResourceLoadTiming;
 class ScriptState;
 class ScriptValue;
 
+// Legacy support for NT1(https://www.w3.org/TR/navigation-timing/).
 class CORE_EXPORT PerformanceTiming final
     : public GarbageCollected<PerformanceTiming>,
       public ScriptWrappable,
       public DOMWindowProperty {
   DEFINE_WRAPPERTYPEINFO();
   USING_GARBAGE_COLLECTED_MIXIN(PerformanceTiming);
 
  public:
   static PerformanceTiming* create(LocalFrame* frame) {
     return new PerformanceTiming(frame);
@@ skipping 65 matching lines @@
   const DocumentParserTiming* documentParserTiming() const;
   const PaintTiming* paintTiming() const;
   DocumentLoader* documentLoader() const;
   DocumentLoadTiming* documentLoadTiming() const;
   ResourceLoadTiming* resourceLoadTiming() const;
 };
 
 }  // namespace blink
 
 #endif  // PerformanceTiming_h