Adding performance tests for HQP that represent importance of optimising HistoryItemsForTerms method

components/omnibox/browser/url_index_private_data.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 "components/omnibox/browser/url_index_private_data.h"
 
 #include <stdint.h>
 
 #include <functional>
 #include <iterator>
@@ skipping 504 matching lines @@
   word_id_history_map_.clear();
   history_id_word_map_.clear();
   history_info_map_.clear();
   word_starts_map_.clear();
 }
 
 URLIndexPrivateData::~URLIndexPrivateData() {}
 
 HistoryIDSet URLIndexPrivateData::HistoryIDSetFromWords(
     const String16Vector& unsorted_words) {
+  SCOPED_UMA_HISTOGRAM_TIMER("Omnibox.HistoryIDSetFromWords");
   // Break the terms down into individual terms (words), get the candidate
   // set for each term, and intersect each to get a final candidate list.
   // Note that a single 'term' from the user's perspective might be
   // a string like "http://www.somewebsite.com" which, from our perspective,
   // is four words: 'http', 'www', 'somewebsite', and 'com'.
   HistoryIDSet history_id_set;
   String16Vector words(unsorted_words);
   // Sort the words into the longest first as such are likely to narrow down
   // the results quicker. Also, single character words are the most expensive
   // to process so save them for last.
@@ skipping 819 matching lines @@
   // First cut: typed count, visit count, recency.
   // TODO(mrossetti): This is too simplistic. Consider an approach which ranks
   // recently visited (within the last 12/24 hours) as highly important. Get
   // input from mpearson.
   if (r1.typed_count() != r2.typed_count())
     return (r1.typed_count() > r2.typed_count());
   if (r1.visit_count() != r2.visit_count())
     return (r1.visit_count() > r2.visit_count());
   return (r1.last_visit() > r2.last_visit());
 }