[USS] Add SyncMetadataStore interface

components/sync/model_impl/on_disk_metadata_change_list.cc

Index: components/sync/model_impl/on_disk_metadata_change_list.cc
diff --git a/components/autofill/core/browser/webdata/autofill_metadata_change_list.cc b/components/sync/model_impl/on_disk_metadata_change_list.cc
similarity index 58%
rename from components/autofill/core/browser/webdata/autofill_metadata_change_list.cc
rename to components/sync/model_impl/on_disk_metadata_change_list.cc
index 24876e4a0cff1b7dd51b5dec518717e20ec9dae8..0f25708fcdfea941583b93a8e338ce30f657223b 100644
--- a/components/autofill/core/browser/webdata/autofill_metadata_change_list.cc
+++ b/components/sync/model_impl/on_disk_metadata_change_list.cc
@@ -1,29 +1,27 @@
-// 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.
 
-#include "components/autofill/core/browser/webdata/autofill_metadata_change_list.h"
+#include "components/sync/model_impl/on_disk_metadata_change_list.h"
 
 #include "base/location.h"
 
 using base::Optional;
 using syncer::ModelError;
 
-namespace autofill {
+namespace syncer {
 
-AutofillMetadataChangeList::AutofillMetadataChangeList(AutofillTable* table,
-                                                       syncer::ModelType type)
+OnDiskMetadataChangeList::OnDiskMetadataChangeList(MetadataTable* table,
+                                                   syncer::ModelType type)
     : table_(table), type_(type) {
   DCHECK(table_);
-  // This should be changed as new autofill types are converted to USS.
-  DCHECK_EQ(syncer::AUTOFILL, type_);
 }
 
-AutofillMetadataChangeList::~AutofillMetadataChangeList() {
+OnDiskMetadataChangeList::~OnDiskMetadataChangeList() {
   DCHECK(!error_);
 }
 
-void AutofillMetadataChangeList::UpdateModelTypeState(
+void OnDiskMetadataChangeList::UpdateModelTypeState(
     const sync_pb::ModelTypeState& model_type_state) {
   if (error_) {
     return;
@@ -34,7 +32,7 @@ void AutofillMetadataChangeList::UpdateModelTypeState(
   }
 }
 
-void AutofillMetadataChangeList::ClearModelTypeState() {
+void OnDiskMetadataChangeList::ClearModelTypeState() {
   if (error_) {
     return;
   }
@@ -44,7 +42,7 @@ void AutofillMetadataChangeList::ClearModelTypeState() {
   }
 }
 
-void AutofillMetadataChangeList::UpdateMetadata(
+void OnDiskMetadataChangeList::UpdateMetadata(
     const std::string& storage_key,
     const sync_pb::EntityMetadata& metadata) {
   if (error_) {
@@ -56,7 +54,7 @@ void AutofillMetadataChangeList::UpdateMetadata(
   }
 }
 
-void AutofillMetadataChangeList::ClearMetadata(const std::string& storage_key) {
+void OnDiskMetadataChangeList::ClearMetadata(const std::string& storage_key) {
   if (error_) {
     return;
   }
@@ -66,10 +64,10 @@ void AutofillMetadataChangeList::ClearMetadata(const std::string& storage_key) {
   }
 }
 
-Optional<ModelError> AutofillMetadataChangeList::TakeError() {
+Optional<ModelError> OnDiskMetadataChangeList::TakeError() {
   Optional<ModelError> temp = error_;
   error_.reset();
   return temp;
 }
 
-}  // namespace autofill
+}  // namespace syncer