Stop doing unnecessary UTF-8 to UTF-16 conversions in JSONWriter.

sync/internal_api/public/base/progress_marker_map.cc

 // 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.
 
 #include "sync/internal_api/public/base/progress_marker_map.h"
 
 #include "base/json/json_writer.h"
 #include "base/json/string_escape.h"
 #include "base/values.h"
 
 namespace syncer {
 
 scoped_ptr<base::DictionaryValue> ProgressMarkerMapToValue(
     const ProgressMarkerMap& marker_map) {
   scoped_ptr<base::DictionaryValue> value(new base::DictionaryValue());
   for (ProgressMarkerMap::const_iterator it = marker_map.begin();
        it != marker_map.end(); ++it) {
     std::string printable_payload;
-    base::JsonDoubleQuote(it->second,
-                          false /* put_in_quotes */,
-                          &printable_payload);
+    base::EscapeJSONString(
+        it->second, false /* put_in_quotes */, &printable_payload);
     value->SetString(ModelTypeToString(it->first), printable_payload);
   }
   return value.Pass();
 }
 
 } // namespace syncer