[Sync] Add support for proxy types

sync/syncable/directory_backing_store.cc

 // Copyright 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/syncable/directory_backing_store.h"
 
 #include "build/build_config.h"
 
 #include <limits>
 
@@ skipping 248 matching lines @@
       return false;
     DCHECK_EQ(db_->GetLastChangeCount(), 1);
 
     sql::Statement s2(db_->GetCachedStatement(
             SQL_FROM_HERE,
             "INSERT OR REPLACE "
             "INTO models (model_id, progress_marker, transaction_version) "
             "VALUES (?, ?, ?)"));
 
     for (int i = FIRST_REAL_MODEL_TYPE; i < MODEL_TYPE_COUNT; ++i) {
+      ModelType type = ModelTypeFromInt(i);
+      if (VirtualTypes().Has(type))
+        continue;
       // We persist not ModelType but rather a protobuf-derived ID.
-      string model_id = ModelTypeEnumToModelId(ModelTypeFromInt(i));
+      string model_id = ModelTypeEnumToModelId(type);
       string progress_marker;
       info.download_progress[i].SerializeToString(&progress_marker);
       s2.BindBlob(0, model_id.data(), model_id.length());
       s2.BindBlob(1, progress_marker.data(), progress_marker.length());
       s2.BindInt64(2, info.transaction_version[i]);
       if (!s2.Run())
         return false;
       DCHECK_EQ(db_->GetLastChangeCount(), 1);
       s2.Reset(true);
     }
@@ skipping 1071 matching lines @@
   }
   query.append(" ) ");
   values.append(" )");
   query.append(values);
   save_statement->Assign(db_->GetUniqueStatement(
       base::StringPrintf(query.c_str(), "metas").c_str()));
 }
 
 }  // namespace syncable
 }  // namespace syncer