sync: Introduce ModelTypeRegistry and helpers

sync/engine/get_updates_processor.h

Index: sync/engine/get_updates_processor.h
diff --git a/sync/engine/get_updates_processor.h b/sync/engine/get_updates_processor.h
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+// Copyright (c) 2014 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 SYNC_ENGINE_GET_UPDATES_PROCESSOR_H
+#define SYNC_ENGINE_GET_UPDATES_PROCESSOR_H
+
+#include <map>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "sync/base/sync_export.h"
+#include "sync/internal_api/public/base/model_type.h"
+#include "sync/internal_api/public/engine/model_safe_worker.h"
+#include "sync/sessions/model_type_registry.h"
+
+namespace sync_pb {
+class GetUpdatesMessage;
+class GetUpdatesResponse;
+}  // namespace sync_pb
+
+namespace syncer {
+
+namespace sessions {
+class StatusController;
+}  // namespace sessions
+
+namespace syncable {
+class Directory;
+}  // namespace syncable
+
+class SyncDirectoryUpdateHandler;
+
+typedef std::vector<const sync_pb::SyncEntity*> SyncEntityList;
+typedef std::map<ModelType, SyncEntityList> TypeSyncEntityMap;
+
+// This class manages the set of per-type syncer objects.
+//
+// It owns these types and hides the details of iterating over all of them.
+// Most methods allow the caller to specify a subset of types on which the
+// operation is to be applied.  It is a logic error if the supplied set of types
+// contains a type which was not previously registered with the manager.
+class SYNC_EXPORT_PRIVATE GetUpdatesProcessor {
+ public:
+  explicit GetUpdatesProcessor(UpdateHandlerMap* update_handler_map);
+  ~GetUpdatesProcessor();
+
+  // Populates a GetUpdates request message with per-type information.
+  void PrepareGetUpdates(ModelTypeSet gu_types,
+                         sync_pb::GetUpdatesMessage* get_updates);
+
+  // Processes a GetUpdates responses for each type.
+  bool ProcessGetUpdatesResponse(
+      ModelTypeSet gu_types,
+      const sync_pb::GetUpdatesResponse& gu_response,
+      sessions::StatusController* status_controller);
+
+  // Applies pending updates for all sync types known to the manager.
+  void ApplyUpdatesForAllTypes(sessions::StatusController* status_controller);
+
+ private:
+  // A map of 'update handlers', one for each enabled type.
+  // This must be kept in sync with the routing info.  Our temporary solution to
+  // that problem is to initialize this map in set_routing_info().
+  UpdateHandlerMap* update_handler_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(GetUpdatesProcessor);
+};
+
+}  // namespace syncer
+
+#endif  // SYNC_ENGINE_GET_UPDATES_PROCESSOR_H_