Massive refactoring of extensions sync code

chrome/browser/sync/glue/extension_sync_traits.h

+// Copyright (c) 2010 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 CHROME_BROWSER_SYNC_GLUE_EXTENSION_SYNC_TRAITS_H_
+#define CHROME_BROWSER_SYNC_GLUE_EXTENSION_SYNC_TRAITS_H_
+#pragma once
+
+#include "chrome/browser/sync/syncable/model_type.h"
+#include "chrome/browser/sync/glue/extension_util.h"
+
+namespace sync_api {
+class BaseNode;
+class WriteNode;
+}  // namespace sync_api
+
+namespace sync_pb {
+class ExtensionSpecifics;
+}  // namespace sync_pb
+
+namespace browser_sync {
+
+// ExtensionSpecificsGetter : BaseNode -> ExtensionSpecifics
+typedef const sync_pb::ExtensionSpecifics& (*ExtensionSpecificsGetter)(
+    const sync_api::BaseNode&);
+
+// A function that sets the appropriate member of the given BaseNode
+// to the given ExtensionSpecifics.
+typedef void (*ExtensionSpecificsSetter)(
+    const sync_pb::ExtensionSpecifics&, sync_api::WriteNode*);
+
+// A function that tries to retrieve an ExtensionSpecifics from an
+// EntitySpecifics.  Returns true and fills in the second argument iff
+// successful.
+typedef bool (*ExtensionSpecificsEntityGetter)(
+    const sync_pb::EntitySpecifics&, sync_pb::ExtensionSpecifics*);
+
+// Represents the properties needed for syncing data types that
+// involve extensions (e.g., "real" extensions, apps).
+struct ExtensionSyncTraits {
+  ExtensionSyncTraits(
+      syncable::ModelType model_type,
+      const char* root_node_tag,
+      const ExtensionTypeSet& allowed_extension_types,
+      ExtensionSpecificsGetter extension_specifics_getter,
+      ExtensionSpecificsSetter extension_specifics_setter,
+      ExtensionSpecificsEntityGetter extension_specifics_entity_getter);
+
+  // The sync type for the data type.
+  const syncable::ModelType model_type;
+  // The tag with which the top-level data type node is marked.
+  const char* const root_node_tag;
+  // The set of allowed ExtensionTypes (not just a single one since
+  // some data types handle more than one).
+  const ExtensionTypeSet allowed_extension_types;
+  // The function that retrieves a ExtensionSpecifics reference (which
+  // may be embedded in another specifics object) from a sync node.
+  const ExtensionSpecificsGetter extension_specifics_getter;
+  // The function that embeds an ExtensionSpecifics into a sync node.
+  const ExtensionSpecificsSetter extension_specifics_setter;
+  // The function that retrieves a ExtensionSpecifics (if possible)
+  // from an EntitySpecifics.
+  ExtensionSpecificsEntityGetter extension_specifics_entity_getter;
+};
+
+// Gets traits for extensions sync.
+ExtensionSyncTraits GetExtensionSyncTraits();
+
+// TODO(akalin): Write GetAppSyncTraits(), too.
+
+}  // namespace browser_sync
+
+#endif  // CHROME_BROWSER_SYNC_GLUE_EXTENSION_SYNC_TRAITS_H_