Add platform files for Background Sync API

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 WebSyncRegistrationOptions {
+    enum NetworkType {
+        NetworkTypeAny = 0,
+        NetworkTypeOffline,
+        NetworkTypeOnline,
+        NetworkTypeNonMobile,
+        NetworkTypeLast = NetworkTypeNonMobile
+    };
+
+    WebSyncRegistrationOptions(NetworkType networkType, bool allowOnBattery, bool idleRequired)
+        : networkType(networkType)
+        , allowOnBattery(allowOnBattery)
+        , idleRequired(idleRequired)
+    {
+    }
+
+    NetworkType networkType;
+    bool allowOnBattery;
+    bool idleRequired;
+};
+
+
+struct WebSyncRegistration {
+    WebSyncRegistration(const WebString& registrationId, const WebSyncRegistrationOptions& options)
+        : id(registrationId)
+        , options(options)
+    {
+    }
+
+    WebString id;
+    WebSyncRegistrationOptions options;
+};
+
+} // namespace blink
+
+#endif // WebSyncRegistration_h