One-time reset of UMA client ids and low entropy source.

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
===================================================================
--- chrome/common/pref_names.cc	(revision 260135)
+++ chrome/common/pref_names.cc	(working copy)
@@ -1362,22 +1362,31 @@
 const char kEulaAccepted[] = "EulaAccepted";
 
 // The metrics client GUID, entropy source and session ID.
-const char kMetricsClientID[] = "user_experience_metrics.client_id";
+// Note: The names client_id2 and low_entropy_source2 are a result of creating
+// new prefs to do a one-time reset of the previous values.
+const char kMetricsClientID[] = "user_experience_metrics.client_id2";
 const char kMetricsSessionID[] = "user_experience_metrics.session_id";
 const char kMetricsLowEntropySource[] =
-    "user_experience_metrics.low_entropy_source";
+    "user_experience_metrics.low_entropy_source2";
 const char kMetricsPermutedEntropyCache[] =
     "user_experience_metrics.permuted_entropy_cache";
 
-// Date/time when the current metrics profile ID was created
-// (which hopefully corresponds to first run).
-const char kMetricsClientIDTimestamp[] =
-    "user_experience_metrics.client_id_timestamp";
+// 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";
 
 // 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).
+const char kMetricsReportingEnabledTimestamp[] =
+    "user_experience_metrics.client_id_timestamp";
 
 // A machine ID used to detect when underlying hardware changes. It is only
 // stored locally and never transmitted in metrics reports.