Componentize //chrome/browser/prefs/tracked.

components/user_prefs/tracked/pref_names.cc

Index: components/user_prefs/tracked/pref_names.cc
diff --git a/components/user_prefs/tracked/pref_names.cc b/components/user_prefs/tracked/pref_names.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a6c73a65228769269481706d175c8e4edd3d98d0
--- /dev/null
+++ b/components/user_prefs/tracked/pref_names.cc
@@ -0,0 +1,13 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/user_prefs/tracked/pref_names.h"
+
+namespace user_prefs {
+
+// A timestamp (stored in base::Time::ToInternalValue format) of the last time
+// a preference was reset.
+const char kPreferenceResetTime[] = "prefs.preference_reset_time";
+
+}  // namespace user_prefs