Sync user's custom spellcheck dictionary

sync/protocol/dictionary_specifics.proto

Index: sync/protocol/dictionary_specifics.proto
diff --git a/sync/protocol/dictionary_specifics.proto b/sync/protocol/dictionary_specifics.proto
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+// 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 the dictionary.
+
+syntax = "proto2";
+
+option optimize_for = LITE_RUNTIME;
+option retain_unknown_fields = true;
+
+package sync_pb;
+
+// Properties of Dictionary objects.
+message DictionarySpecifics {
+  // A spelling which when typed is treated as a correctly spelled word.
+  optional string word = 1;
+}