Gather stability prefs into managing objects.

components/metrics/metrics_pref_names.h

Index: components/metrics/metrics_pref_names.h
diff --git a/components/metrics/metrics_pref_names.h b/components/metrics/metrics_pref_names.h
index df25e3854a91ae33bed8e39e943f05b2d099bf79..a9188028bdf97135f0e7983fb23e206919f80d31 100644
--- a/components/metrics/metrics_pref_names.h
+++ b/components/metrics/metrics_pref_names.h
@@ -30,6 +30,8 @@ extern const char kMetricsReportingEnabled[];
 extern const char kMetricsReportingEnabledTimestamp[];
 extern const char kMetricsSessionID[];
 extern const char kMetricsLastSeenPrefix[];
+
+// Preferences for recording stability logs.
 extern const char kStabilityBreakpadRegistrationSuccess[];
 extern const char kStabilityBreakpadRegistrationFail[];
 extern const char kStabilityChildProcessCrashCount[];
@@ -44,9 +46,7 @@ extern const char kStabilityExtensionRendererFailedLaunchCount[];
 extern const char kStabilityExtensionRendererLaunchCount[];
 extern const char kStabilityExitedCleanly[];
 extern const char kStabilityIncompleteSessionEndCount[];
-extern const char kStabilityLastTimestampSec[];
 extern const char kStabilityLaunchCount[];
-extern const char kStabilityLaunchTimeSec[];
 extern const char kStabilityPageLoadCount[];
 extern const char kStabilityRendererCrashCount[];
 extern const char kStabilityRendererFailedLaunchCount[];
@@ -58,6 +58,8 @@ extern const char kStabilitySessionEndCompleted[];
 extern const char kStabilityStatsBuildTime[];
 extern const char kStabilityStatsVersion[];
 extern const char kStabilityVersionMismatchCount[];
+
+// Preferences for generating metrics at uninstall time.
 extern const char kUninstallLaunchCount[];
 extern const char kUninstallMetricsPageLoadCount[];
 extern const char kUninstallMetricsUptimeSec[];