Add Prerender type to NavigationType for nav timing 2

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

 /*
  * 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 18 matching lines @@
  */
 
 #include "core/timing/PerformanceNavigation.h"
 
 #include "bindings/core/v8/ScriptValue.h"
 #include "bindings/core/v8/V8ObjectBuilder.h"
 #include "core/frame/LocalFrame.h"
 #include "core/loader/DocumentLoader.h"
 #include "core/loader/FrameLoaderTypes.h"
 
+// Legacy support for NT1(https://www.w3.org/TR/navigation-timing/).
 namespace blink {
 
 PerformanceNavigation::PerformanceNavigation(LocalFrame* frame)
     : DOMWindowProperty(frame) {}
 
 unsigned short PerformanceNavigation::type() const {
   if (!frame())
     return kTypeNavigate;
 
   DocumentLoader* documentLoader = frame()->loader().documentLoader();
@@ skipping 31 matching lines @@
   result.addNumber("type", type());
   result.addNumber("redirectCount", redirectCount());
   return result.scriptValue();
 }
 
 DEFINE_TRACE(PerformanceNavigation) {
   DOMWindowProperty::trace(visitor);
 }
 
 }  // namespace blink