[NoStatePrefetch] Fix the PrefetchAge histogram to match histograms.xml

chrome/browser/prerender/prerender_histograms.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/prerender/prerender_histograms.h"
 
 #include <string>
 
 #include "base/format_macros.h"
 #include "base/logging.h"
@@ skipping 450 matching lines @@
 void PrerenderHistograms::RecordPrefetchFirstContentfulPaintTime(
     Origin origin,
     bool is_no_store,
     bool was_hidden,
     base::TimeDelta time,
     base::TimeDelta prefetch_age) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (!prefetch_age.is_zero()) {
     DCHECK_NE(origin, ORIGIN_NONE);
-    RecordHistogramTime(
-        GetHistogramName(origin, IsOriginWash(), "Prerender.PrefetchAge"),
-        base::TimeDelta::FromMilliseconds(10), base::TimeDelta::FromMinutes(30),
-        prefetch_age, 50);
+    RecordHistogramTime(GetHistogramName(origin, IsOriginWash(), "PrefetchAge"),
+                        base::TimeDelta::FromMilliseconds(10),
+                        base::TimeDelta::FromMinutes(30), prefetch_age, 50);
   }
 
   std::string histogram_base_name;
   if (prefetch_age.is_zero()) {
     histogram_base_name = "PrefetchTTFCP.Reference";
   } else {
     histogram_base_name = prefetch_age < base::TimeDelta::FromMinutes(
                                              net::HttpCache::kPrefetchReuseMins)
                               ? "PrefetchTTFCP.Warm"
                               : "PrefetchTTFCP.Cold";
   }
 
   histogram_base_name += is_no_store ? ".NoStore" : ".Cacheable";
   histogram_base_name += FirstContentfulPaintHiddenName(was_hidden);
   std::string histogram_name =
       GetHistogramName(origin, IsOriginWash(), histogram_base_name);
 
   RecordHistogramTime(histogram_name, base::TimeDelta::FromMilliseconds(10),
                       base::TimeDelta::FromMinutes(2), time, 50);
 }
 
 bool PrerenderHistograms::IsOriginWash() const {
   if (!WithinWindow())
     return false;
   return origin_wash_;
 }
 
 }  // namespace prerender