Sync MDP: reimplement value conversions ontop of visitors

components/sync/protocol/proto_old_value_conversions.h

Index: components/sync/protocol/proto_old_value_conversions.h
diff --git a/components/sync/protocol/proto_value_conversions.h b/components/sync/protocol/proto_old_value_conversions.h
similarity index 98%
copy from components/sync/protocol/proto_value_conversions.h
copy to components/sync/protocol/proto_old_value_conversions.h
index 8147d1a8539d6feaf5459406c4143db6d0be78ad..f4ecd843a4f48f09d63e0e3a8dbf95f0c694a66a 100644
--- a/components/sync/protocol/proto_value_conversions.h
+++ b/components/sync/protocol/proto_old_value_conversions.h
@@ -4,8 +4,8 @@
 
 // Keep this file in sync with the .proto files in this directory.
 
-#ifndef COMPONENTS_SYNC_PROTOCOL_PROTO_VALUE_CONVERSIONS_H_
-#define COMPONENTS_SYNC_PROTOCOL_PROTO_VALUE_CONVERSIONS_H_
+#ifndef COMPONENTS_SYNC_PROTOCOL_PROTO_OLD_VALUE_CONVERSIONS_H_
+#define COMPONENTS_SYNC_PROTOCOL_PROTO_OLD_VALUE_CONVERSIONS_H_
 
 #include <memory>
 
@@ -94,6 +94,7 @@ class WifiCredentialSpecifics;
 // TODO(akalin): Improve enum support.
 
 namespace syncer {
+namespace old {
 
 // Ownership of all returned DictionaryValues are transferred to the
 // caller.
@@ -319,6 +320,7 @@ std::unique_ptr<base::DictionaryValue> AttachmentIdProtoToValue(
 std::unique_ptr<base::DictionaryValue> EntityMetadataToValue(
     const sync_pb::EntityMetadata& metadata);
 
+}  // namespace old
 }  // namespace syncer
 
-#endif  // COMPONENTS_SYNC_PROTOCOL_PROTO_VALUE_CONVERSIONS_H_
+#endif  // COMPONENTS_SYNC_PROTOCOL_PROTO_OLD_VALUE_CONVERSIONS_H_