[Sync] USS: Implement SimpleMetadataChangeList.

sync/internal_api/public/simple_metadata_change_list.h

Index: sync/internal_api/public/simple_metadata_change_list.h
diff --git a/sync/internal_api/public/simple_metadata_change_list.h b/sync/internal_api/public/simple_metadata_change_list.h
index f302b12ff93109a0fc5fbb56c3ce3cdc16ff721a..9daaee49b1bc697fee54dc1fb73da443cf7a7d7e 100644
--- a/sync/internal_api/public/simple_metadata_change_list.h
+++ b/sync/internal_api/public/simple_metadata_change_list.h
@@ -5,11 +5,15 @@
 #ifndef SYNC_INTERNAL_API_PUBLIC_SIMPLE_METADATA_CHANGE_LIST_H_
 #define SYNC_INTERNAL_API_PUBLIC_SIMPLE_METADATA_CHANGE_LIST_H_
 
+#include <map>
 #include <string>
 
 #include "sync/api/metadata_change_list.h"
 #include "sync/api/model_type_store.h"
 #include "sync/base/sync_export.h"
+#include "sync/internal_api/public/non_blocking_sync_common.h"

[skym, 2016/02/18 16:11:10]

Don't think you need this anymore.

+#include "sync/protocol/data_type_state.pb.h"
+#include "sync/protocol/entity_metadata.pb.h"
 
 namespace syncer_v2 {
 
@@ -18,6 +22,20 @@ namespace syncer_v2 {
 // requested transfers them to the store/write batch.
 class SYNC_EXPORT SimpleMetadataChangeList : public MetadataChangeList {
  public:
+  enum ChangeType { UPDATE, CLEAR };
+
+  struct MetadataChange {
+    ChangeType type;
+    sync_pb::EntityMetadata metadata;
+  };
+
+  struct DataTypeStateChange {
+    ChangeType type;
+    sync_pb::DataTypeState state;
+  };
+
+  typedef std::map<std::string, MetadataChange> MetadataChanges;
+
   SimpleMetadataChangeList();
   ~SimpleMetadataChangeList() override;
 
@@ -28,11 +46,19 @@ class SYNC_EXPORT SimpleMetadataChangeList : public MetadataChangeList {
                       const sync_pb::EntityMetadata& metadata) override;
   void ClearMetadata(const std::string& client_tag) override;
 
+  const MetadataChanges& GetMetadataChanges() const;
+  bool HasDataTypeStateChange() const;
+  const DataTypeStateChange& GetDataTypeStateChange() const;
+
   // Moves all currently accumulated changes into the write batch, clear out
   // local copies. Calling this multiple times will work, but should not be
   // necessary.
-  void TranfserChanges(ModelTypeStore* store,
+  void TransferChanges(ModelTypeStore* store,
                        ModelTypeStore::WriteBatch* write_batch);
+
+ private:
+  MetadataChanges metadata_changes_;
+  scoped_ptr<DataTypeStateChange> state_change_;
 };
 
 }  // namespace syncer_v2