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

sync/internal_api/public/base/progress_marker_map.cc

Index: sync/internal_api/public/base/progress_marker_map.cc
diff --git a/sync/internal_api/public/base/progress_marker_map.cc b/sync/internal_api/public/base/progress_marker_map.cc
index b2810134ebf30859e01725efabdc18dafdda2292..82b93e84ed375f7511a7ace83858546d1ff887ee 100644
--- a/sync/internal_api/public/base/progress_marker_map.cc
+++ b/sync/internal_api/public/base/progress_marker_map.cc
@@ -15,10 +15,8 @@ scoped_ptr<base::DictionaryValue> ProgressMarkerMapToValue(
   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);
+    std::string printable_payload = base::EscapeBytesAsInvalidJSONString(
+        it->second, false /* put_in_quotes */);
     value->SetString(ModelTypeToString(it->first), printable_payload);
   }
   return value.Pass();