History init: add metrics and skip migration.

components/history/core/browser/history_backend.cc

Index: components/history/core/browser/history_backend.cc
diff --git a/components/history/core/browser/history_backend.cc b/components/history/core/browser/history_backend.cc
index bb21144ebac05b66290d4fb0da88d18b8de1ad8b..14855781aacc2b3cd6f670c9ddd8db0a7de82a2e 100644
--- a/components/history/core/browser/history_backend.cc
+++ b/components/history/core/browser/history_backend.cc
@@ -651,6 +651,9 @@ void HistoryBackend::InitImpl(
       bool kill_db = scheduled_kill_db_;
       if (kill_db)
         KillHistoryDatabase();
+
+      // The frequency of this UMA will indicate how often history
+      // initialization fails.
       UMA_HISTOGRAM_BOOLEAN("History.AttemptedToFixProfileError", kill_db);
     }  // Falls through.
     case sql::INIT_TOO_NEW: {