Enable sync for the settings from the Extension Settings API.

chrome/common/pref_names.h

 // Copyright (c) 2011 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 475 matching lines @@
 extern const char kKeepEverythingSynced[];
 extern const char kSyncBookmarks[];
 extern const char kSyncPasswords[];
 extern const char kSyncPreferences[];
 extern const char kSyncApps[];
 extern const char kSyncAutofill[];
 extern const char kSyncAutofillProfile[];
 extern const char kSyncThemes[];
 extern const char kSyncTypedUrls[];
 extern const char kSyncExtensions[];
+extern const char kSyncExtensionSettings[];
 extern const char kSyncManaged[];
 extern const char kSyncSuppressStart[];
 extern const char kGoogleServicesUsername[];
 extern const char kSyncUsingOAuth[];
 extern const char kSyncUsingSecondaryPassphrase[];
 extern const char kEncryptionBootstrapToken[];
 extern const char kAutofillProfileMigrated[];
 extern const char kAcknowledgedSyncTypes[];
 
 extern const char kWebAppCreateOnDesktop[];
@@ skipping 78 matching lines @@
 
 extern const char kUserCreatedLoginItem[];
 extern const char kBackgroundModeEnabled[];
 
 extern const char kDevicePolicyRefreshRate[];
 extern const char kUserPolicyRefreshRate[];
 
 }  // namespace prefs
 
 #endif  // CHROME_COMMON_PREF_NAMES_H_