Make calls to AtomicString(const String&) explicit in html/

Source/core/html/track/TextTrackCue.h

 /*
  * Copyright (C) 2011 Google Inc.  All rights reserved.
  * Copyright (C) 2012, 2013 Apple 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.
@@ skipping 38 matching lines @@
     {
         DEFINE_STATIC_LOCAL(const AtomicString, cue, ("cue", AtomicString::ConstructFromLiteral));
         return cue;
     }
 
     virtual ~TextTrackCue() { }
 
     TextTrack* track() const;
     void setTrack(TextTrack*);
 
-    const String& id() const { return m_id; }
-    void setId(const String&);
+    const AtomicString& id() const { return m_id; }
+    void setId(const AtomicString&);
 
     double startTime() const { return m_startTime; }
     void setStartTime(double, ExceptionState&);
 
     double endTime() const { return m_endTime; }
     void setEndTime(double, ExceptionState&);
 
     bool pauseOnExit() const { return m_pauseOnExit; }
     void setPauseOnExit(bool);
 
@@ skipping 23 matching lines @@
     DEFINE_ATTRIBUTE_EVENT_LISTENER(enter);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(exit);
 
 protected:
     TextTrackCue(double start, double end);
 
     void cueWillChange();
     virtual void cueDidChange();
 
 private:
-    String m_id;
+    AtomicString m_id;
     double m_startTime;
     double m_endTime;
     int m_cueIndex;
 
     TextTrack* m_track;
 
     bool m_isActive : 1;
     bool m_pauseOnExit : 1;
 };
 
 } // namespace WebCore
 
 #endif