[Sync] Create UserEventService.

components/sync/user_events/user_event_service.cc

+// 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/sync/user_events/user_event_service.h"
+
+#include <utility>
+
+#include "base/bind.h"
+#include "base/memory/ptr_util.h"
+#include "base/rand_util.h"
+#include "components/sync/driver/sync_service.h"
+#include "components/sync/model/model_type_sync_bridge.h"
+#include "components/sync/protocol/sync.pb.h"
+#include "components/sync/user_events/user_event_sync_bridge.h"
+
+using sync_pb::UserEventSpecifics;
+
+namespace syncer {
+
+UserEventService::UserEventService(SyncService* sync_service,
+                                   std::unique_ptr<UserEventSyncBridge> bridge)
+    : sync_service_(sync_service),
+      bridge_(std::move(bridge)),
+      session_id_(base::RandUint64()) {}
+
+UserEventService::~UserEventService() {}
+
+void UserEventService::Shutdown() {}
+
+void UserEventService::RecordUserEvent(
+    std::unique_ptr<UserEventSpecifics> specifics) {
+  if (CanRecordEvent(*specifics)) {
+    DCHECK(!specifics->has_session_id());
+    specifics->set_session_id(session_id_);
+    bridge_->RecordUserEvent(std::move(specifics));
+  }
+}
+
+void UserEventService::RecordUserEvent(const UserEventSpecifics& specifics) {
+  RecordUserEvent(base::MakeUnique<UserEventSpecifics>(specifics));
+}
+
+base::WeakPtr<ModelTypeSyncBridge> UserEventService::GetSyncBridge() {
+  return bridge_->AsWeakPtr();
+}
+
+bool UserEventService::CanRecordEvent(const UserEventSpecifics& specifics) {
+  return sync_service_ != nullptr && sync_service_->IsEngineInitialized() &&
+         sync_service_->GetPreferredDataTypes().Has(HISTORY_DELETE_DIRECTIVES);

[Patrick Noland, 2017/05/08 22:42:37]

Can you make HISTORY_DELETE_DIRECTIVES a constant and explain its significance?

[skym, 2017/05/08 23:35:27]

How about a comment right here? It already is a constant.

[Patrick Noland, 2017/05/08 23:41:29]

That's fine, as long as you give context for its significance

+}
+
+}  // namespace syncer