Merge 260349 "One-time reset of UMA client ids and low entropy s..."

> One-time reset of UMA client ids and low entropy source. 
> 
> As we've observed a "cloned install" effect in the wild, 
> doing this will de-clone such installs. (Which will work 
> in conjunction with other measures to prevent new instances 
> of cloned installs appearing). 
> 
> Renames client id and low entropy source prefs so that they 
> are re-generated the next time Chrome runs. Makes the code 
> clear the old prefs, so that they are cleaned up in 
> existing local state files (in a future milestone, we can 
> remove them completely - http://crbug.com/357704).
> 
> (Note: Does not rename kMetricsPermutedEntropyCache as 
> that pref is reset when the low entropy id is re-generated.) 
> 
> BUG=357618
> TEST=Running an UMA-enabled build should result in local state 
> getting new values for user_experience_metrics.low_entropy_source2 
> and user_experience_metrics.client_id2 and removal of prefs 
> low_entropy_source and client_id.
> NOTRY=true
> 
> Review URL: https://codereview.chromium.org/217083002

TBR=asvitkine@chromium.org

Review URL: https://codereview.chromium.org/218493016

git-svn-id: svn://svn.chromium.org/chrome/branches/1916/src@260952 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 49 insertions, 20 deletions

diff --git a/chrome/browser/metrics/metrics_log.cc b/chrome/browser/metrics/metrics_log.cc
index f9721f4..4fd74e7 100644
--- a/chrome/browser/metrics/metrics_log.cc
+++ b/chrome/browser/metrics/metrics_log.cc
@@ -84,7 +84,7 @@ std::string GetMetricsEnabledDate(PrefService* pref) {
     return "0";
   }
 
-  return pref->GetString(prefs::kMetricsClientIDTimestamp);
+  return pref->GetString(prefs::kMetricsReportingEnabledTimestamp);
 }
 
 OmniboxEventProto::InputType AsOmniboxEventInputType(
diff --git a/chrome/browser/metrics/metrics_log_unittest.cc b/chrome/browser/metrics/metrics_log_unittest.cc
index 9f3ca7c..eba9ed1 100644
--- a/chrome/browser/metrics/metrics_log_unittest.cc
+++ b/chrome/browser/metrics/metrics_log_unittest.cc
@@ -160,8 +160,8 @@ class TestMetricsLog : public MetricsLog {
  private:
   void InitPrefs() {
     prefs_->SetInt64(prefs::kInstallDate, kInstallDate);
-    prefs_->SetString(prefs::kMetricsClientIDTimestamp,
-                     base::Int64ToString(kEnabledDate));
+    prefs_->SetString(prefs::kMetricsReportingEnabledTimestamp,
+                      base::Int64ToString(kEnabledDate));
 #if defined(OS_CHROMEOS)
     prefs_->SetInteger(prefs::kStabilityChildProcessCrashCount, 10);
     prefs_->SetInteger(prefs::kStabilityOtherUserCrashCount, 11);
diff --git a/chrome/browser/metrics/metrics_service.cc b/chrome/browser/metrics/metrics_service.cc
index 7155c40..ecd3114 100644
--- a/chrome/browser/metrics/metrics_service.cc
+++ b/chrome/browser/metrics/metrics_service.cc
@@ -437,9 +437,9 @@ void MetricsService::RegisterPrefs(PrefRegistrySimple* registry) {
   DCHECK(IsSingleThreaded());
   registry->RegisterBooleanPref(prefs::kMetricsResetIds, false);
   registry->RegisterStringPref(prefs::kMetricsClientID, std::string());
+  registry->RegisterInt64Pref(prefs::kMetricsReportingEnabledTimestamp, 0);
   registry->RegisterIntegerPref(prefs::kMetricsLowEntropySource,
                                 kLowEntropySourceNotSet);
-  registry->RegisterInt64Pref(prefs::kMetricsClientIDTimestamp, 0);
   registry->RegisterInt64Pref(prefs::kStabilityLaunchTimeSec, 0);
   registry->RegisterInt64Pref(prefs::kStabilityLastTimestampSec, 0);
   registry->RegisterStringPref(prefs::kStabilityStatsVersion, std::string());
@@ -484,6 +484,11 @@ void MetricsService::RegisterPrefs(PrefRegistrySimple* registry) {
   registry->RegisterInt64Pref(prefs::kUninstallLastLaunchTimeSec, 0);
   registry->RegisterInt64Pref(prefs::kUninstallLastObservedRunTimeSec, 0);
 
+  // TODO(asvitkine): Remove these once a couple of releases have passed.
+  // http://crbug.com/357704
+  registry->RegisterStringPref(prefs::kMetricsOldClientID, std::string());
+  registry->RegisterIntegerPref(prefs::kMetricsOldLowEntropySource, 0);
+
 #if defined(OS_ANDROID)
   RegisterPrefsAndroid(registry);
 #endif  // defined(OS_ANDROID)
@@ -646,9 +651,14 @@ void MetricsService::ForceClientIdCreation() {
   client_id_ = GenerateClientID();
   pref->SetString(prefs::kMetricsClientID, client_id_);
 
-  // Might as well make a note of how long this ID has existed
-  pref->SetString(prefs::kMetricsClientIDTimestamp,
-                  base::Int64ToString(Time::Now().ToTimeT()));
+  if (pref->GetString(prefs::kMetricsOldClientID).empty()) {
+    // Record the timestamp of when the user opted in to UMA.
+    pref->SetInt64(prefs::kMetricsReportingEnabledTimestamp,
+                   Time::Now().ToTimeT());
+  } else {
+    UMA_HISTOGRAM_BOOLEAN("UMA.ClientIdMigrated", true);
+  }
+  pref->ClearPref(prefs::kMetricsOldClientID);
 }
 
 void MetricsService::EnableRecording() {
@@ -1225,12 +1235,6 @@ int MetricsService::GetLowEntropySource() {
   // Otherwise, skip to generating a new value.
   if (!command_line->HasSwitch(switches::kResetVariationState)) {
     int value = local_state->GetInteger(prefs::kMetricsLowEntropySource);
-    // Old versions of the code would generate values in the range of [1, 8192],
-    // before the range was switched to [0, 8191] and then to [0, 7999]. Map
-    // 8192 to 0, so that the 0th bucket remains uniform, while re-generating
-    // the low entropy source for old values in the [8000, 8191] range.
-    if (value == 8192)
-      value = 0;
     // If the value is outside the [0, kMaxLowEntropySize) range, re-generate
     // it below.
     if (value >= 0 && value < kMaxLowEntropySize) {
@@ -1243,6 +1247,7 @@ int MetricsService::GetLowEntropySource() {
   UMA_HISTOGRAM_BOOLEAN("UMA.GeneratedLowEntropySource", true);
   low_entropy_source_ = GenerateLowEntropySource();
   local_state->SetInteger(prefs::kMetricsLowEntropySource, low_entropy_source_);
+  local_state->ClearPref(prefs::kMetricsOldLowEntropySource);
   metrics::CachingPermutedEntropyProvider::ClearCache(local_state);
 
   return low_entropy_source_;
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 678ee6d..c79a100 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -1362,22 +1362,31 @@ const char kDisableSSLRecordSplitting[] = "ssl.ssl_record_splitting.disabled";
 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.
diff --git a/chrome/common/pref_names.h b/chrome/common/pref_names.h
index d79f0a5..573f834 100644
--- a/chrome/common/pref_names.h
+++ b/chrome/common/pref_names.h
@@ -435,8 +435,10 @@ extern const char kMetricsClientID[];
 extern const char kMetricsSessionID[];
 extern const char kMetricsLowEntropySource[];
 extern const char kMetricsPermutedEntropyCache[];
-extern const char kMetricsClientIDTimestamp[];
+extern const char kMetricsOldClientID[];
+extern const char kMetricsOldLowEntropySource[];
 extern const char kMetricsReportingEnabled[];
+extern const char kMetricsReportingEnabledTimestamp[];
 extern const char kMetricsMachineId[];
 extern const char kMetricsResetIds[];
 // Android has it's own metric / crash reporting implemented in Android
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index bad41e4..cb68f31 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -27714,6 +27714,14 @@ other types of suffix sets.
   <summary>Whether the scroll is executed on main thread.</summary>
 </histogram>
 
+<histogram name="UMA.ClientIdMigrated" enum="BooleanMigrated">
+  <owner>asvitkine@chromium.org</owner>
+  <summary>
+    Recorded when the one-time UMA client id reset was performed (and the client
+    id of this user was migrated).
+  </summary>
+</histogram>
+
 <histogram name="UMA.CollectExternalEventsTime" units="milliseconds">
   <owner>asvitkine@chromium.org</owner>
   <summary>
@@ -30021,6 +30029,11 @@ other types of suffix sets.
   <int value="1" label="Matched"/>
 </enum>
 
+<enum name="BooleanMigrated" type="int">
+  <int value="0" label="Not migrated"/>
+  <int value="1" label="Migrated"/>
+</enum>
+
 <enum name="BooleanOrphan" type="int">
   <int value="0" label="Non-orphan"/>
   <int value="1" label="Orphan"/>