HTMLMediaElement shouldn't call currentTime() when we HAVE_NOTHING.

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 313 matching lines @@
     , m_duration(std::numeric_limits<double>::quiet_NaN())
     , m_lastTimeUpdateEventWallTime(0)
     , m_lastTimeUpdateEventMovieTime(std::numeric_limits<double>::max())
     , m_loadState(WaitingForSource)
     , m_deferredLoadState(NotDeferred)
     , m_deferredLoadTimer(this, &HTMLMediaElement::deferredLoadTimerFired)
     , m_webLayer(0)
     , m_preload(MediaPlayer::Auto)
     , m_displayMode(Unknown)
     , m_cachedTime(MediaPlayer::invalidTime())
-    , m_cachedTimeWallClockUpdateTime(0)
-    , m_minimumWallClockTimeToCacheMediaTime(0)
     , m_fragmentStartTime(MediaPlayer::invalidTime())
     , m_fragmentEndTime(MediaPlayer::invalidTime())
     , m_pendingActionFlags(0)
     , m_userGestureRequiredForPlay(false)
     , m_playing(false)
     , m_shouldDelayLoadEvent(false)
     , m_haveFiredLoadedData(false)
     , m_active(true)
     , m_autoplaying(true)
     , m_muted(false)
@@ skipping 437 matching lines @@
 
         // 4.6 - If seeking is true, set it to false.
         m_seeking = false;
 
         // 4.7 - Set the current playback position to 0.
         //       Set the official playback position to 0.
         //       If this changed the official playback position, then queue a task to fire a simple event named timeupdate at the media element.
         // FIXME: Add support for firing this event.
 
         // 4.8 - Set the initial playback position to 0.
-        // FIXME: Make this less subtle. The position only becomes 0 because of the createMediaPlayer() call
-        // above.
-        refreshCachedTime();
+        // FIXME: Make this less subtle. The position only becomes 0 because the ready state is HAVE_NOTHING.
         invalidateCachedTime();
 
         // 4.9 - Set the timeline offset to Not-a-Number (NaN).
         // 4.10 - Update the duration attribute to Not-a-Number (NaN).
 
 
         updateMediaController();
         updateActiveTextTrackCues(0);
     }
 
@@ skipping 1234 matching lines @@
     return webMediaPlayer() && webMediaPlayer()->hasAudio();
 }
 
 bool HTMLMediaElement::seeking() const
 {
     return m_seeking;
 }
 
 void HTMLMediaElement::refreshCachedTime() const
 {
-    if (!webMediaPlayer())
+    if (!webMediaPlayer() || m_readyState < HAVE_METADATA)

[philipj_slow, 2014/09/03 09:11:00]

This reminds me of http://crbug.com/382721 which was intended to guarantee that
m_readyState >= HAVE_METADATA implies webMediaPlayer(), i.e. !webMediaPlayer()
implies m_readyState < HAVE_METADATA.

Is the "m_readyState < HAVE_METADATA" still reachable, or could it simply be
asserted?

[scherkus (not reviewing), 2014/09/03 17:03:45]

While m_readyState >= HAVE_METADATA certainly implies webMediaPlayer(), the
converse isn't necessarily true: we can still HAVE_NOTHING and be
NETWORK_LOADING as we're currently trying to fetch the initial data to advance
to the HAVE_METADATA state

As a side, it'd be nice to tighten up the WebMediaPlayer contract to imply that
that they start in the HAVE_NOTHING state so that implementations don't have to
do stuff like:
https://code.google.com/p/chromium/codesearch#search/&q=SetReadyState%5C(WebM...

         return;
 
     m_cachedTime = webMediaPlayer()->currentTime();
-    m_cachedTimeWallClockUpdateTime = WTF::currentTime();
 }
 
 void HTMLMediaElement::invalidateCachedTime()
 {
     WTF_LOG(Media, "HTMLMediaElement::invalidateCachedTime");
-
-    // Don't try to cache movie time when playback first starts as the time reported by the engine
-    // sometimes fluctuates for a short amount of time, so the cached time will be off if we take it
-    // too early.
-    static const double minimumTimePlayingBeforeCacheSnapshot = 0.5;
-
-    m_minimumWallClockTimeToCacheMediaTime = WTF::currentTime() + minimumTimePlayingBeforeCacheSnapshot;
     m_cachedTime = MediaPlayer::invalidTime();
 }
 
 // playback state
 double HTMLMediaElement::currentTime() const
 {
-#if LOG_CACHED_TIME_WARNINGS
-    static const double minCachedDeltaForWarning = 0.01;
-#endif
-
     if (m_readyState == HAVE_NOTHING)
         return 0;
 
     if (m_seeking) {
         WTF_LOG(Media, "HTMLMediaElement::currentTime - seeking, returning %f", m_lastSeekTime);
         return m_lastSeekTime;
     }
 
     if (m_cachedTime != MediaPlayer::invalidTime() && m_paused) {
 #if LOG_CACHED_TIME_WARNINGS
+        static const double minCachedDeltaForWarning = 0.01;
         double delta = m_cachedTime - webMediaPlayer()->currentTime();
         if (delta > minCachedDeltaForWarning)
             WTF_LOG(Media, "HTMLMediaElement::currentTime - WARNING, cached time is %f seconds off of media time when paused", delta);
 #endif
         return m_cachedTime;
     }
 
     refreshCachedTime();
 
     return m_cachedTime;
@@ skipping 1312 matching lines @@
         m_networkState = NETWORK_IDLE;
 
     // 5 - Set the element's delaying-the-load-event flag to false. This stops delaying the load event.
     setShouldDelayLoadEvent(false);
 
     // 6 - Abort the overall resource selection algorithm.
     m_currentSourceNode = nullptr;
 
     // Reset m_readyState since m_player is gone.
     m_readyState = HAVE_NOTHING;
+    invalidateCachedTime();
     updateMediaController();
     updateActiveTextTrackCues(0);
 }
 
 void HTMLMediaElement::clearMediaPlayerAndAudioSourceProviderClientWithoutLocking()
 {
 #if ENABLE(WEB_AUDIO)
     if (audioSourceProvider())
         audioSourceProvider()->setClient(0);
 #endif
@@ skipping 560 matching lines @@
 
 #if ENABLE(WEB_AUDIO)
 void HTMLMediaElement::clearWeakMembers(Visitor* visitor)
 {
     if (!visitor->isAlive(m_audioSourceNode) && audioSourceProvider())
         audioSourceProvider()->setClient(0);
 }
 #endif
 
 }