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

components/history/core/browser/typed_url_sync_metadata_database.h

+// Copyright (c) 2017 The Chromium Authors. All rights reserved.

[sky, 2017/03/01 04:15:24]

no (c)

[Gang Wu, 2017/03/02 05:41:12]

Done.

+// 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"
+
+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 urls. Datatype state table contains the state of typed url

[sky, 2017/03/01 04:15:24]

urls->url

[Gang Wu, 2017/03/02 05:41:12]

Done.

+// 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 |model_type| and fill |metadata_batch|
+  // with it.
+  bool GetAllSyncMetadata(syncer::ModelType model_type,

[sky, 2017/03/01 04:15:24]

Why does this need to take a model_type? Same comment for all these functions.

[Gang Wu, 2017/03/02 05:41:12]

I was thinking about merge with AutofillTable's GetAllSyncMetadata  and other
functions, making an interface class and let HistoryDatabase class and
AutofillTable class to be derived  class. but after discuss with team, it seems
not necessary, so I should remove model_type. 

+                          syncer::MetadataBatch* metadata_batch);
+
+  // Update the metadata row for |model_type|, keyed by |storage_key|, to
+  // contain the contents of |metadata|.
+  bool UpdateSyncMetadata(syncer::ModelType model_type,
+                          const std::string& storage_key,
+                          const sync_pb::EntityMetadata& metadata);
+
+  // Remove the metadata row of type |model_type| keyed by |storage_key|.
+  bool ClearSyncMetadata(syncer::ModelType model_type,
+                         const std::string& storage_key);
+
+  // Update the stored sync state for the |model_type|.
+  bool UpdateModelTypeState(syncer::ModelType model_type,
+                            const sync_pb::ModelTypeState& model_type_state);
+
+  // Clear the stored sync state for |model_type|.
+  bool ClearModelTypeState(syncer::ModelType model_type);
+
+ protected:
+  // Returns the database for the functions in this interface.
+  virtual sql::Connection& GetDB() = 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:
+  // Ensures typed_url_sync_metadata table exists.
+  bool InitTypedURLSyncMetadataTable();
+
+  // Ensures typed_url_model_type_state table exists.
+  bool InitModelTypeStateTable();
+
+  // Read all sync_pb::EntityMetadata for |model_type| and fill
+  // |metadata_records| with it.
+  bool GetAllSyncEntityMetadata(syncer::ModelType model_type,
+                                syncer::EntityMetadataMap* metadata_records);
+
+  // Read sync_pb::ModelTypeState for |model_type| and fill |state| with it.
+  bool GetModelTypeState(syncer::ModelType model_type,
+                         sync_pb::ModelTypeState* state);
+
+  DISALLOW_COPY_AND_ASSIGN(TypedURLSyncMetadataDatabase);
+};
+
+}  // namespace history
+
+#endif  // COMPONENTS_HISTORY_CORE_BROWSER_TYPED_URL_SYNC_METADATA_DATABASE_H_