Add a base::Feature for the pref service.

chrome/common/chrome_features.cc

 // Copyright 2016 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 "chrome/common/chrome_features.h"
 
 #include "extensions/features/features.h"
 #include "ppapi/features/features.h"
 
 namespace features {
@@ skipping 197 matching lines @@
                                         base::FEATURE_DISABLED_BY_DEFAULT};
 #endif  // OS_WIN
 
 #if BUILDFLAG(ENABLE_PLUGINS)
 // Prefer HTML content by hiding Flash from the list of plugins.
 // https://crbug.com/626728
 const base::Feature kPreferHtmlOverPlugins{"PreferHtmlOverPlugins",
                                            base::FEATURE_DISABLED_BY_DEFAULT};
 #endif
 
+// Enables the pref service. See https://crbug.com/654988.
+const base::Feature kPrefService{"PrefService",
+                                 base::FEATURE_DISABLED_BY_DEFAULT};
+
 #if defined(OS_CHROMEOS)
 // The lock screen will be preloaded so it is instantly available when the user
 // locks the Chromebook device.
 const base::Feature kPreloadLockScreen{"PreloadLockScreen",
                                        base::FEATURE_ENABLED_BY_DEFAULT};
 #endif
 
 // Enables the Print Scaling feature in print preview.
 #if BUILDFLAG(ENABLE_PRINT_PREVIEW)
 const base::Feature kPrintPdfAsImage{"PrintPdfAsImage",
@@ skipping 58 matching lines @@
 // Enables or disables emoji, handwriting and voice input on opt-in IME menu.
 const base::Feature kEHVInputOnImeMenu{"EmojiHandwritingVoiceInput",
                                        base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Enables or disables flash component updates on Chrome OS.
 const base::Feature kCrosCompUpdates{"CrosCompUpdates",
                                      base::FEATURE_ENABLED_BY_DEFAULT};
 #endif  // defined(OS_CHROMEOS)
 
 }  // namespace features