Clear client id prefs when opting out of UMA.

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 37 matching lines @@
 
 // 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";
 
 // Boolean that specifies whether or not crash reporting and metrics reporting
 // are sent over the network for analysis.
 const char kMetricsReportingEnabled[] =
     "user_experience_metrics.reporting_enabled";
 
-// Date/time when the user opted in to UMA and generated the client id for the
-// very first time (local machine time, stored as a 64-bit time_t value).
+// Date/time when the user opted in to UMA and generated the client id most
+// recently (local machine time, stored as a 64-bit time_t value).
 const char kMetricsReportingEnabledTimestamp[] =
     "user_experience_metrics.client_id_timestamp";
 
 // The metrics client session ID.
 const char kMetricsSessionID[] = "user_experience_metrics.session_id";
 
 // The prefix of the last-seen timestamp for persistent histogram files.
 // Values are named for the files themselves.
 const char kMetricsLastSeenPrefix[] =
     "user_experience_metrics.last_seen.";
@@ skipping 119 matching lines @@
 // Dictionary for measuring cellular data used by UMA service during last 7
 // days.
 const char kUmaCellDataUse[] = "user_experience_metrics.uma_cell_datause";
 
 // Dictionary for measuring cellular data used by user including chrome services
 // per day.
 const char kUserCellDataUse[] = "user_experience_metrics.user_call_datause";
 
 }  // namespace prefs
 }  // namespace metrics