[MediaControls] Listen to durationchange instead of letting HTML call methods of MediaControls

third_party/WebKit/Source/core/html/shadow/MediaControls.cpp

 /*
  * Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2011, 2012 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:
  * 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
@@ skipping 687 matching lines @@
   // become transparent in that case.
   if (mediaElement().paused()) {
     makeOpaque();
     return;
   }
 
   if (isVisible() && shouldHideMediaControls())
     makeTransparent();
 }
 
+void MediaControls::onDurationChange() {
+  m_timeline->setDuration(mediaElement().duration());
+  updateCurrentTimeDisplay();
+
+  // 'durationchange' might be called in a paused state. The controls should not
+  // become transparent in that case.
+  if (mediaElement().paused()) {
+    makeOpaque();
+    return;
+  }
+
+  if (isVisible() && shouldHideMediaControls())
+    makeTransparent();

[mlamouri (slow - plz ping), 2016/12/13 20:00:00]

I don't think you need to do all the transparency checks. The media controls are
using timeupdate to auto-hide. Duration change shouldn't worry about that. Only
the two first lines are needed.

[Zhiqiang Zhang (Slow), 2016/12/13 20:13:20]

Done.

+}
+
 void MediaControls::onPlay() {
   updatePlayState();
   m_timeline->setPosition(mediaElement().currentTime());
   updateCurrentTimeDisplay();
 
   startHideMediaControlsTimer();
 }
 
 void MediaControls::onPause() {
   updatePlayState();
@@ skipping 203 matching lines @@
   visitor->trace(m_overflowMenu);
   visitor->trace(m_overflowList);
   visitor->trace(m_castButton);
   visitor->trace(m_overlayCastButton);
   visitor->trace(m_mediaEventListener);
   visitor->trace(m_windowEventListener);
   HTMLDivElement::trace(visitor);
 }
 
 }  // namespace blink