Gather stability prefs into managing objects.

components/metrics/metrics_pref_names.cc

Index: components/metrics/metrics_pref_names.cc
diff --git a/components/metrics/metrics_pref_names.cc b/components/metrics/metrics_pref_names.cc
index c5ad9c6abf561e8c49822a7e58283da8777dfe70..ea3fd3892ae2a1a877700f163886d84ee14b367f 100644
--- a/components/metrics/metrics_pref_names.cc
+++ b/components/metrics/metrics_pref_names.cc
@@ -128,19 +128,10 @@ const char kStabilityExtensionRendererLaunchCount[] =
 const char kStabilityIncompleteSessionEndCount[] =
     "user_experience_metrics.stability.incomplete_session_end_count";
 
-// Time when the app was last known to be running, in seconds since
-// the epoch.
-const char kStabilityLastTimestampSec[] =
-    "user_experience_metrics.stability.last_timestamp_sec";
-
 // Number of times the application was launched since last report.
 const char kStabilityLaunchCount[] =
     "user_experience_metrics.stability.launch_count";
 
-// Time when the app was last launched, in seconds since the epoch.
-const char kStabilityLaunchTimeSec[] =
-    "user_experience_metrics.stability.launch_time_sec";
-
 // Number of times a page load event occurred since the last report.
 const char kStabilityPageLoadCount[] =
     "user_experience_metrics.stability.page_load_count";