Add a couple of notifications related settings to app/extensions sync:

chrome/browser/sync/protocol/app_specifics.proto

 // Copyright (c) 2010 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.
 //
 // Sync protocol datatype extension for apps.
 
 // Update proto_value_conversions{.h,.cc,_unittest.cc} if you change
 // any fields in this file.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 option retain_unknown_fields = true;
 
 package sync_pb;
 
 import "sync.proto";
 import "extension_specifics.proto";
 
+// Settings related to push notifications for apps.
+message AppNotificationSettings {
+  // Whether or not the user has setup notifications at least once.
+  // The value for this field will start out false and will be set
+  // to true when the user accepts receiving notifications for the
+  // first time and then it will always remain true.
+  optional bool initial_setup_done = 1;
+
+  // Whether or not the user has disabled notifications.
+  optional bool disabled = 2;
+}
+
 // Properties of app sync objects.
 //
 // For now, an app is just an extension.  We keep the two data types
 // separate for future-proofing purposes.
 message AppSpecifics {
   // Extension data.
   optional ExtensionSpecifics extension = 1;
+
+  // Notification settings.
+  optional AppNotificationSettings notification_settings = 2; 
 }
 
 extend EntitySpecifics {
   optional AppSpecifics app = 48364;
 }