[BackgroundSync Cleanup] Remove periodic sync code

third_party/WebKit/Source/modules/background_sync/SyncManager.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 SyncManager_h
 #define SyncManager_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "platform/heap/Handle.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class ExecutionContext;
 class SyncRegistrationOptions;
 class ScriptPromise;
 class ScriptState;
 class ServiceWorkerRegistration;
 
 class SyncManager final : public GarbageCollected<SyncManager> , public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static SyncManager* create(ServiceWorkerRegistration* registration)
     {
         return new SyncManager(registration);
     }
 
-    unsigned long minAllowablePeriod();
-
     ScriptPromise registerFunction(ScriptState*, ExecutionContext*, const String&);
     ScriptPromise getTags(ScriptState*);
 
     DECLARE_TRACE();
 
 private:
     explicit SyncManager(ServiceWorkerRegistration*);
 
     Member<ServiceWorkerRegistration> m_registration;
 };
 
 } // namespace blink
 
 #endif // SyncManager_h