Add Precache.Fetch.Begin user action.

components/precache/content/precache_manager.cc

 // Copyright 2013 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/precache/content/precache_manager.h"
 
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
+#include "base/metrics/user_metrics.h"
+#include "base/metrics/user_metrics_action.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/time/time.h"
 #include "components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.h"
 #include "components/history/core/browser/history_service.h"
 #include "components/precache/core/precache_database.h"
 #include "components/precache/core/precache_switches.h"
 #include "components/precache/core/proto/precache.pb.h"
 #include "components/precache/core/proto/unfinished_work.pb.h"
 #include "components/prefs/pref_service.h"
@@ skipping 250 matching lines @@
         *unfinished_work, unfinished_work->top_host_size(),
         unfinished_work->resource_size());
     unfinished_work.reset(new PrecacheUnfinishedWork);
   }
   // If this prefetch is new, set the start time.
   if (!unfinished_work->has_start_time())
     unfinished_work->set_start_time(base::Time::Now().ToInternalValue());
   unfinished_work_ = std::move(unfinished_work);
   bool needs_top_hosts = unfinished_work_->top_host_size() == 0;
 
+  base::RecordAction(base::UserMetricsAction("Precache.Fetch.Begin"));
+
   if (IsInExperimentGroup()) {
     BrowserThread::PostTask(
         BrowserThread::DB, FROM_HERE,
         base::Bind(&PrecacheDatabase::DeleteExpiredPrecacheHistory,
                    base::Unretained(precache_database_.get()),
                    base::Time::Now()));
 
     // Request NumTopHosts() top hosts. Note that PrecacheFetcher is further
     // bound by the value of PrecacheConfigurationSettings.top_sites_count, as
     // retrieved from the server.
@@ skipping 204 matching lines @@
       this));
   precache_fetcher_->Start();
 }
 
 void PrecacheManager::OnHostsReceivedThenDone(
     const history::TopHostsList& host_counts) {
   OnDone();
 }
 
 }  // namespace precache