Resolve the issue of unexpected currentTime values when setting currentTime from seeking event

Source/core/html/HTMLMediaElement.cpp

 /*
  * 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 1699 matching lines @@
     refreshCachedTime();
     double now = currentTime();
 
     // 2 - If the element's seeking IDL attribute is true, then another instance of this algorithm is
     // already running. Abort that other instance of the algorithm without waiting for the step that
     // it is running to complete.
     // Nothing specific to be done here.
 
     // 3 - Set the seeking IDL attribute to true.
     // The flag will be cleared when the engine tells us the time has actually changed.
+    bool previousSeekStillPending = m_seeking;
     m_seeking = true;
 
     // 5 - If the new playback position is later than the end of the media resource, then let it be the end
     // of the media resource instead.
     time = min(time, duration());
 
     // 6 - If the new playback position is less than the earliest possible position, let it be that position instead.
     time = max(time, 0.0);
 
     // Ask the media engine for the time value in the movie's time scale before comparing with current time. This
@@ skipping 20 matching lines @@
     bool noSeekRequired = !seekableRanges->length() || (time == now && displayMode() != Poster);
 
     // Always notify the media engine of a seek if the source is not closed. This ensures that the source is
     // always in a flushed state when the 'seeking' event fires.
     if (m_mediaSource && m_mediaSource->isClosed())
         noSeekRequired = false;
 
     if (noSeekRequired) {
         if (time == now) {
             scheduleEvent(EventTypeNames::seeking);
+            if (previousSeekStillPending)
+                return;
             // FIXME: There must be a stable state before timeupdate+seeked are dispatched and seeking
             // is reset to false. See http://crbug.com/266631
             scheduleTimeupdateEvent(false);
             scheduleEvent(EventTypeNames::seeked);
         }
         m_seeking = false;
         return;
     }
     time = seekableRanges->nearest(time);
 
@@ skipping 1872 matching lines @@
     return fastHasAttribute(controlsAttr);
 }
 
 void HTMLMediaElement::trace(Visitor* visitor)
 {
     Supplementable<HTMLMediaElement>::trace(visitor);
     HTMLElement::trace(visitor);
 }
 
 }