Restoring the chrome variatioons client, with a fix for browser_test failures caused by it.

chrome/common/pref_names.h

 // Copyright (c) 2012 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.
 
 // Constants for the names of various preferences, for easier changing.
 
 #ifndef CHROME_COMMON_PREF_NAMES_H_
 #define CHROME_COMMON_PREF_NAMES_H_
 #pragma once
 
@@ skipping 345 matching lines @@
 
 extern const char kMetricsClientID[];
 extern const char kMetricsSessionID[];
 extern const char kMetricsClientIDTimestamp[];
 extern const char kMetricsReportingEnabled[];
 extern const char kMetricsInitialLogsXml[];
 extern const char kMetricsInitialLogsProto[];
 extern const char kMetricsOngoingLogsXml[];
 extern const char kMetricsOngoingLogsProto[];
 
+extern const char kVariationsSeed[];
+
 extern const char kProfileLastUsed[];
 extern const char kProfilesLastActive[];
 extern const char kProfilesNumCreated[];
 extern const char kProfileInfoCache[];
 extern const char kProfileCreatedByVersion[];
 
 extern const char kProfileMetrics[];
 extern const char kProfilePrefix[];
 
 extern const char kStabilityExitedCleanly[];
@@ skipping 322 matching lines @@
 #endif
 
 extern const char kInManagedMode[];
 
 extern const char kNetworkProfileWarningsLeft[];
 extern const char kNetworkProfileLastWarningTime[];
 
 }  // namespace prefs
 
 #endif  // CHROME_COMMON_PREF_NAMES_H_