Move content/child/background_sync to Blink.

third_party/WebKit/public/platform/modules/background_sync/WebSyncRegistration.h

-// 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.
-
-#ifndef WebSyncRegistration_h
-#define WebSyncRegistration_h
-
-#include "public/platform/WebPrivatePtr.h"
-#include "public/platform/WebString.h"
-
-namespace blink {
-
-struct WebSyncRegistration {
-  enum NetworkState {
-    NetworkStateAny = 0,
-    NetworkStateAvoidCellular,
-    NetworkStateOnline,
-    NetworkStateLast = NetworkStateOnline
-  };
-
-  enum { UNREGISTERED_SYNC_ID = -1 };
-
-  WebSyncRegistration()
-      : id(UNREGISTERED_SYNC_ID),
-        tag(""),
-        networkState(NetworkState::NetworkStateOnline) {}
-
-  WebSyncRegistration(int64_t id,
-                      const WebString& registrationTag,
-                      NetworkState networkState)
-      : id(id), tag(registrationTag), networkState(networkState) {}
-
-  /* Internal identity; not exposed to JS API. */
-  int64_t id;
-
-  WebString tag;
-  NetworkState networkState;
-};
-
-}  // namespace blink
-
-#endif  // WebSyncRegistration_h