[BackgroundSync] Initial land of the BackgroundSyncManager

content/browser/background_sync/background_sync.proto

+// Copyright 2015 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.
+
+syntax = "proto2";
+
+option optimize_for = LITE_RUNTIME;
+
+package content;
+
+message BackgroundSyncRegistrationProto {
+  required int64 id = 1;
+  required string name = 2;
+  optional int64 min_period = 3;
+}
+
+message BackgroundSyncRegistrationsProto {
+  repeated BackgroundSyncRegistrationProto registration = 1;
+  required int64 next_registration_id = 2;
+}