Delete code corresponding to old UMA prefs.

components/metrics/metrics_pref_names.cc

 // Copyright 2014 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/metrics/metrics_pref_names.h"
 
 namespace metrics {
 namespace prefs {
 
 // Set once, to the current epoch time, on the first run of chrome on this
@@ skipping 14 matching lines @@
 // The metrics entropy source.
 // Note: The name low_entropy_source2 is a result of creating
 // new prefs to do a one-time reset of the previous values.
 const char kMetricsLowEntropySource[] =
     "user_experience_metrics.low_entropy_source2";
 
 // A machine ID used to detect when underlying hardware changes. It is only
 // stored locally and never transmitted in metrics reports.
 const char kMetricsMachineId[] = "user_experience_metrics.machine_id";
 
-// Old client id and low entropy source values, cleared the first time this
-// version is launched.
-// TODO(asvitkine): Delete these after a few releases have gone by and old
-// values have been cleaned up. http://crbug.com/357704
-const char kMetricsOldClientID[] = "user_experience_metrics.client_id";
-const char kMetricsOldLowEntropySource[] =
-    "user_experience_metrics.low_entropy_source";
-
 // Array of strings that are each UMA logs that were not sent because the
 // browser terminated before these accumulated metrics could be sent.  These
 // logs typically include histograms and memory reports, as well as ongoing
 // user activities.
 const char kMetricsOngoingLogs[] =
     "user_experience_metrics.ongoing_logs_list";
 
 // Boolean that indicates a cloned install has been detected and the metrics
 // client id and low entropy source should be reset.
 const char kMetricsResetIds[] = "user_experience_metrics.reset_metrics_ids";
@@ skipping 75 matching lines @@
     "user_experience_metrics.stability.stats_version";
 
 // The keys below are strictly increasing counters over the lifetime of
 // a chrome installation. They are (optionally) sent up to the uninstall
 // survey in the event of uninstallation.
 const char kUninstallLaunchCount[] = "uninstall_metrics.launch_count";
 const char kUninstallMetricsUptimeSec[] = "uninstall_metrics.uptime_sec";
 
 }  // namespace prefs
 }  // namespace metrics