Fixes play seek when user sets loop after ended.

Source/core/html/HTMLMediaElement.h

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 393 matching lines @@
     // This does not check user gesture restrictions.
     void playInternal();
 
     void gesturelessInitialPlayHalted();
     void autoplayMediaEncountered();
     void allowVideoRendering();
 
     void updateVolume();
     void updatePlayState();
     bool potentiallyPlaying() const;
-    bool endedPlayback() const;
     bool stoppedDueToErrors() const;
     bool couldPlayIfEnoughData() const;
 
+    // Generally the presence of the loop attribute should be considered to mean playback
+    // has not "ended", as "ended" and "looping" are mutually exclusive. See
+    // https://html.spec.whatwg.org/multipage/embedded-content.html#ended-playback
+    enum class LoopCondition { Included, Ignored };
+    bool endedPlayback(LoopCondition = LoopCondition::Included) const;
+
     void setShouldDelayLoadEvent(bool);
     void invalidateCachedTime();
     void refreshCachedTime() const;
 
     bool hasMediaControls() const;
     void ensureMediaControls();
     void configureMediaControls();
 
     virtual void* preDispatchEventHandler(Event*) override final;
 
@@ skipping 183 matching lines @@
 inline bool isHTMLMediaElement(const HTMLElement& element)
 {
     return isHTMLAudioElement(element) || isHTMLVideoElement(element);
 }
 
 DEFINE_HTMLELEMENT_TYPE_CASTS_WITH_FUNCTION(HTMLMediaElement);
 
 } // namespace blink
 
 #endif // HTMLMediaElement_h