[BackgroundSync Cleanup] Remove periodic sync code

content/browser/background_sync/background_sync_registration_handle.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 CONTENT_BROWSER_BACKGROUND_SYNC_BACKGROUND_SYNC_REGISTRATION_HANDLE_H_
 #define CONTENT_BROWSER_BACKGROUND_SYNC_BACKGROUND_SYNC_REGISTRATION_HANDLE_H_
 
 #include <stdint.h>
 
 #include "base/callback.h"
@@ skipping 35 matching lines @@
 
   // Unregisters the background sync registration.  Calls |callback|
   // with BACKGROUND_SYNC_STATUS_OK if it succeeds.
   void Unregister(int64_t service_worker_id, const StatusCallback& callback);
 
   // Runs |callback| when the registration associated with |handle_id|
   // completes.The provided status is BACKGROUND_SYNC_STATUS_OK if the operation
   // succeeded. The provided state is BackgroundSyncState::SUCCESS on success,
   // BACKGRUOND_SYNC_STATE_FAILED on final failure, and
   // BackgroundSyncState::UNREGISTERED if the registration was unregistered
-  // before it could complete. NotifyWhenFinished should only be called for
-  // SYNC_ONE_SHOT registrations.
+  // before it could complete.
   void NotifyWhenFinished(const StatusAndStateCallback& callback);
 
   // Returns true if the handle is backed by a BackgroundSyncRegistration in the
   // BackgroundSyncManager.
   bool IsValid() const;
 
   HandleId handle_id() const { return handle_id_; }
 
  private:
   friend class BackgroundSyncManager;
@@ skipping 18 matching lines @@
   // This is owned by background_sync_manager_ and is valid until handle_id_ is
   // released in the destructor or background_sync_manager_ has been destroyed.
   BackgroundSyncRegistration* registration_;
 
   DISALLOW_COPY_AND_ASSIGN(BackgroundSyncRegistrationHandle);
 };
 
 }  // namespace
 
 #endif  // CONTENT_BROWSER_BACKGROUND_SYNC_BACKGROUND_SYNC_REGISTRATION_HANDLE_H_