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 1c4aa6a0436526c8c33c228708c1e585b47a3127..5ba3e5658df4e9f66c56be35dadd2aed6d5f0a5d 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: {