Add History.TopHostsVisitsByRank UMA metric.

components/history/core/browser/history_database.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/history/core/browser/history_database.h"
 
 #include <algorithm>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/containers/hash_tables.h"
 #include "base/files/file_util.h"
 #include "base/metrics/histogram.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/rand_util.h"
 #include "base/strings/string_util.h"
 #include "base/time/time.h"
+#include "components/history/core/browser/url_utils.h"
 #include "sql/statement.h"
 #include "sql/transaction.h"
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
 #include "base/mac/mac_util.h"
 #endif
 
 namespace history {
 
 namespace {
@@ skipping 170 matching lines @@
   url_sql.BindInt64(0, one_month_ago.ToInternalValue());
 
   // Collect a map from host to visit count.
   base::hash_map<std::string, int> host_count;
   while (url_sql.Step()) {
     GURL url(url_sql.ColumnString(0));
     if (!(url.is_valid() && (url.SchemeIsHTTPOrHTTPS() || url.SchemeIs("ftp"))))
       continue;
 
     int64 visit_count = url_sql.ColumnInt64(1);
-    std::string host = url.host();
-    if (base::StartsWithASCII(host, "www.", true))
-      host.assign(host, 4, std::string::npos);
-    host_count[host] += visit_count;
+    host_count[HostForTopHosts(url)] += visit_count;
 
     // kMaxHostsInMemory is well above typical values for
     // History.MonthlyHostCount, but here to guard against unbounded memory
     // growth in the event of an atypical history.
     if (host_count.size() >= kMaxHostsInMemory)
       break;
   }
 
   // Collect the top 100 hosts by visit count, into the range
   // [top_hosts.begin(), middle).
@@ skipping 285 matching lines @@
       "SET visit_time = visit_time + 11644473600000000 "
       "WHERE id IN (SELECT id FROM visits WHERE visit_time > 0);"));
   ignore_result(db_.Execute(
       "UPDATE segment_usage "
       "SET time_slot = time_slot + 11644473600000000 "
       "WHERE id IN (SELECT id FROM segment_usage WHERE time_slot > 0);"));
 }
 #endif
 
 }  // namespace history