Move content/child/background_sync to Blink.

third_party/WebKit/public/platform/modules/background_sync/WebSyncProvider.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 WebSyncProvider_h
-#define WebSyncProvider_h
-
-#include "public/platform/WebCallbacks.h"
-#include "public/platform/WebCommon.h"
-#include "public/platform/WebString.h"
-#include "public/platform/WebVector.h"
-#include "public/platform/modules/background_sync/WebSyncError.h"
-#include "public/platform/modules/background_sync/WebSyncRegistration.h"
-
-#include <memory>
-
-namespace blink {
-
-class WebServiceWorkerRegistration;
-using WebSyncRegistrationCallbacks =
-    WebCallbacks<std::unique_ptr<WebSyncRegistration>, const WebSyncError&>;
-using WebSyncGetRegistrationsCallbacks =
-    WebCallbacks<const WebVector<WebSyncRegistration*>&, const WebSyncError&>;
-
-class WebSyncProvider {
- public:
-  virtual ~WebSyncProvider() {}
-
-  // Takes ownership of the WebSyncRegistrationCallbacks.
-  // Does not take ownership of the WebServiceWorkerRegistration.
-  virtual void registerBackgroundSync(const WebSyncRegistration*,
-                                      WebServiceWorkerRegistration*,
-                                      WebSyncRegistrationCallbacks*) = 0;
-
-  // Takes ownership of the WebSyncGetRegistrationsCallbacks.
-  // Does not take ownership of the WebServiceWorkerRegistration.
-  virtual void getRegistrations(WebServiceWorkerRegistration*,
-                                WebSyncGetRegistrationsCallbacks*) = 0;
-};
-
-}  // namespace blink
-
-#endif  // WebSyncProvider_h