Add remote_install flag to extension sync data.

sync/protocol/extension_specifics.proto

 // 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.
 //
 // Sync protocol datatype extension for extensions.
 
 // Update proto_value_conversions{.h,.cc,_unittest.cc} if you change
 // any fields in this file.
 
 syntax = "proto2";
@@ skipping 17 matching lines @@
   // which case the default one (i.e., the one for the Chrome
   // Extensions Gallery) is used.
   optional string update_url = 3;
   // Whether or not this extension is enabled.
   optional bool enabled = 4;
   // Whether or not this extension is enabled in incognito mode.
   optional bool incognito_enabled = 5;
 
   // The name of the extension. Used for bookmark apps.
   optional string name = 6;
+
+  // Whether this extension was installed remotely, and hasn't been approved by
+  // a user in chrome yet.
+  optional bool remote_install = 7;
 }