Basic UkmService implementation

components/ukm/ukm_pref_names.cc

Index: components/ukm/ukm_pref_names.cc
diff --git a/components/ukm/ukm_pref_names.cc b/components/ukm/ukm_pref_names.cc
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index 0000000000000000000000000000000000000000..75b374ff074ab4b92903398e23891b79f9fd4ec6
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+++ b/components/ukm/ukm_pref_names.cc
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+// Copyright 2017 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/ukm/ukm_pref_names.h"
+
+namespace ukm {
+namespace prefs {
+
+// A random uint64 value unique for each chrome install.
+const char kUkmClientId[] = "ukm.client_id";
+
+// Preference which stores serialized UKM logs to be uploaded.
+const char kUkmPersistedLogs[] = "ukm.persisted_logs";
+
+}  // namespace prefs
+}  // namespace ukm