[USS] Add SyncMetadataStore interface

components/sync/model_impl/sync_metadata_store_change_list.h

-// Copyright 2016 The Chromium Authors. All rights reserved.
+// Copyright 2017 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.
 
-#ifndef COMPONENTS_AUTOFILL_CORE_BROWSER_WEBDATA_AUTOFILL_METADATA_CHANGE_LIST_H_
-#define COMPONENTS_AUTOFILL_CORE_BROWSER_WEBDATA_AUTOFILL_METADATA_CHANGE_LIST_H_
+#ifndef COMPONENTS_SYNC_MODEL_IMPL_SYNC_METADATA_STORE_CHANGE_LIST_H_
+#define COMPONENTS_SYNC_MODEL_IMPL_SYNC_METADATA_STORE_CHANGE_LIST_H_
 
 #include <string>
 
 #include "base/optional.h"
-#include "components/autofill/core/browser/webdata/autofill_table.h"
 #include "components/sync/base/model_type.h"
 #include "components/sync/model/metadata_change_list.h"
 #include "components/sync/model/model_error.h"
-#include "components/sync/model/sync_error.h"
+#include "components/sync/model/sync_metadata_store.h"
 #include "components/sync/protocol/entity_metadata.pb.h"
 #include "components/sync/protocol/model_type_state.pb.h"
 
-namespace autofill {
+namespace syncer {
 
-// A thin wrapper around an AutofillTable that implements sync's
-// MetadataChangeList interface. Changes are passed directly into the table and
-// not stored inside this object. Since the table calls can fail, |TakeError()|
+// A thin wrapper around an SyncMetadataStore that implements sync's
+// MetadataChangeList interface. Changes are passed directly into the store and
+// not stored inside this object. Since the store calls can fail, |TakeError()|
 // must be called before this object is destroyed to check whether any
 // operations failed.
-class AutofillMetadataChangeList : public syncer::MetadataChangeList {
+class SyncMetadataStoreChangeList : public MetadataChangeList {
  public:
-  AutofillMetadataChangeList(AutofillTable* table, syncer::ModelType type);
-  ~AutofillMetadataChangeList() override;
+  SyncMetadataStoreChangeList(SyncMetadataStore* store, syncer::ModelType type);
+  ~SyncMetadataStoreChangeList() override;
 
-  // syncer::MetadataChangeList implementation.
+  // MetadataChangeList implementation.
   void UpdateModelTypeState(
       const sync_pb::ModelTypeState& model_type_state) override;
   void ClearModelTypeState() override;
   void UpdateMetadata(const std::string& storage_key,
                       const sync_pb::EntityMetadata& metadata) override;
   void ClearMetadata(const std::string& storage_key) override;
-
-  // Returns the value of |error_| and unsets it.
   base::Optional<syncer::ModelError> TakeError();
 
  private:
-  // The autofill table to store metadata in; always outlives |this|.
-  AutofillTable* table_;
+  // The metadata store to store metadata in; always outlives |this|.
+  SyncMetadataStore* store_;
 
   // The sync model type for this metadata.
   syncer::ModelType type_;
 
   // The first error encountered by this object, if any.
   base::Optional<syncer::ModelError> error_;
 };
 
-}  // namespace autofill
+}  // namespace syncer
 
-#endif  // COMPONENTS_AUTOFILL_CORE_BROWSER_WEBDATA_AUTOFILL_METADATA_CHANGE_LIST_H_
+#endif  // COMPONENTS_SYNC_MODEL_IMPL_SYNC_METADATA_STORE_CHANGE_LIST_H_