[sync] Add typed url sync metadata to the history db

components/history/core/browser/typed_url_sync_metadata_database.h

Index: components/history/core/browser/typed_url_sync_metadata_database.h
diff --git a/components/history/core/browser/typed_url_sync_metadata_database.h b/components/history/core/browser/typed_url_sync_metadata_database.h
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+++ b/components/history/core/browser/typed_url_sync_metadata_database.h
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+// 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_HISTORY_CORE_BROWSER_TYPED_URL_SYNC_METADATA_DATABASE_H_
+#define COMPONENTS_HISTORY_CORE_BROWSER_TYPED_URL_SYNC_METADATA_DATABASE_H_
+
+#include "base/macros.h"
+#include "components/sync/base/model_type.h"
+#include "components/sync/model/metadata_batch.h"
+#include "sql/meta_table.h"
+
+namespace sql {
+class Connection;
+}
+
+namespace history {
+
+// A sync metadata database needs to maintain two tables: entity metadata table
+// and datatype state table. Entity metadata table contains metadata(sync
+// states) for each url. Datatype state table contains the state of typed url
+// datatype.
+class TypedURLSyncMetadataDatabase {
+ public:
+  // Must call InitVisitTable() before using to make sure the database is
+  // initialized.
+  TypedURLSyncMetadataDatabase();
+  virtual ~TypedURLSyncMetadataDatabase();
+
+  // Read all the stored metadata for typed URL and fill |metadata_batch|
+  // with it.
+  bool GetAllSyncMetadata(syncer::MetadataBatch* metadata_batch);
+
+  // Update the metadata row for typed URL, keyed by |storage_key|, to
+  // contain the contents of |metadata|.
+  bool UpdateSyncMetadata(const std::string& storage_key,
+                          const sync_pb::EntityMetadata& metadata);
+
+  // Remove the metadata row of typed URL keyed by |storage_key|.
+  bool ClearSyncMetadata(const std::string& storage_key);
+
+  // Update the stored sync state for the typed URL.
+  bool UpdateModelTypeState(const sync_pb::ModelTypeState& model_type_state);
+
+  // Clear the stored sync state for typed URL.
+  bool ClearModelTypeState();
+
+ protected:
+  // Returns the database for the functions in this interface.
+  virtual sql::Connection& GetDB() = 0;
+
+  // Returns MetaTable, so this sync can store ModelTypeState in MetaTable.
+  // Check if GetMetaTable().GetVersionNumber() is greater than 0 to make sure
+  // MetaTable is initialed.
+  virtual sql::MetaTable& GetMetaTable() = 0;
+
+  // Called by the derived classes on initialization to make sure the tables
+  // and indices are properly set up. Must be called before anything else.
+  bool InitSyncTable();
+
+ private:
+  // Read all sync_pb::EntityMetadata for typed URL and fill
+  // |metadata_records| with it.
+  bool GetAllSyncEntityMetadata(syncer::EntityMetadataMap* metadata_records);
+
+  // Read sync_pb::ModelTypeState for typed URL and fill |state| with it.
+  bool GetModelTypeState(sync_pb::ModelTypeState* state);
+
+  DISALLOW_COPY_AND_ASSIGN(TypedURLSyncMetadataDatabase);
+};
+
+}  // namespace history
+
+#endif  // COMPONENTS_HISTORY_CORE_BROWSER_TYPED_URL_SYNC_METADATA_DATABASE_H_