[Sync] Hook UserEvents into sync.

components/sync/driver/sync_driver_switches.cc

 // 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/sync/driver/sync_driver_switches.h"
 
 namespace switches {
 
 // Allows overriding the deferred init fallback timeout.
 const char kSyncDeferredStartupTimeoutSeconds[] =
@@ skipping 18 matching lines @@
 // purpose is to speed up integration tests. The normal delay allows coalescing
 // and prevention of server overload, so don't use this unless you're really
 // sure
 // that it's what you want.
 const char kSyncShortNudgeDelayForTest[] = "sync-short-nudge-delay-for-test";
 
 // Enables clearing of sync data when a user enables passphrase encryption.
 const base::Feature kSyncClearDataOnPassphraseEncryption{
     "ClearSyncDataOnPassphraseEncryption", base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Gates registration and construction of user events machinery.
+const base::Feature kSyncUserEvents{"SyncUserEvents",
+                                    base::FEATURE_DISABLED_BY_DEFAULT};
+
+// Enables USS implementation of Autocomplete datatype.
+const base::Feature kSyncUSSAutocomplete{"SyncUSSAutocomplete",
+                                         base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Enables USS implementation of DeviceInfo datatype. This flag controls whether
 // SyncableService based or ModelTypeSyncBridge based implementation is used for
 // DeviceInfo type.
 const base::Feature kSyncUSSDeviceInfo{"EnableSyncUSSDeviceInfo",
                                        base::FEATURE_DISABLED_BY_DEFAULT};
 
-// Enables USS implementation of Autocomplete datatype.
-const base::Feature kSyncUSSAutocomplete{"SyncUSSAutocomplete",
-                                         base::FEATURE_DISABLED_BY_DEFAULT};
-
 // Enables USS implementation of typed URL datatype.
 const base::Feature kSyncUSSTypedURL{"SyncUSSTypedURL",
                                      base::FEATURE_DISABLED_BY_DEFAULT};
 
 }  // namespace switches