Update first-sync-delay metric name to be consistent with others and add it to

chrome/browser/sync/profile_sync_service.cc

Index: chrome/browser/sync/profile_sync_service.cc
diff --git a/chrome/browser/sync/profile_sync_service.cc b/chrome/browser/sync/profile_sync_service.cc
index 955a4b6eb90c57232cd69c6f1f22a15fef2fbb48..862d01466e9142493111dd88123ccfa49ded9287 100644
--- a/chrome/browser/sync/profile_sync_service.cc
+++ b/chrome/browser/sync/profile_sync_service.cc
@@ -690,8 +690,8 @@ void ProfileSyncService::StartUpSlowBackendComponents(
     backup_start_time_ = base::Time::Now();
 
   if (backend_mode_ == SYNC && !backup_start_time_.is_null()) {
-    UMA_HISTOGRAM_TIMES("first-sync-delay-by-backup",
-                        base::Time::Now() - backup_start_time_);
+    UMA_HISTOGRAM_MEDIUM_TIMES("Sync.FirstSyncDelayByBackup",
+                               base::Time::Now() - backup_start_time_);
     backup_start_time_ = base::Time();
   }