FileWriter should not use deprecated {,un}setPendingActivity

Source/modules/filesystem/FileWriter.h

 /*
  * Copyright (C) 2010 Google Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 54 matching lines @@
     ReadyState readyState() const { return m_readyState; }
     FileError* error() const { return m_error.get(); }
 
     // WebFileWriterClient
     virtual void didWrite(long long bytes, bool complete) OVERRIDE;
     virtual void didTruncate() OVERRIDE;
     virtual void didFail(blink::WebFileError) OVERRIDE;
 
     // ActiveDOMObject
     virtual void stop() OVERRIDE;
+    virtual bool hasPendingActivity() const OVERRIDE;
 
     // EventTarget
     virtual const AtomicString& interfaceName() const OVERRIDE;
     virtual ExecutionContext* executionContext() const OVERRIDE { return ActiveDOMObject::executionContext(); }
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(writestart);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(progress);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(write);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(abort);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(error);
@@ skipping 32 matching lines @@
     long long m_truncateLength;
     long long m_numAborts;
     long long m_recursionDepth;
     double m_lastProgressNotificationTimeMS;
     RefPtrWillBeMember<Blob> m_blobBeingWritten;
 };
 
 } // namespace WebCore
 
 #endif // FileWriter_h