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

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

Index: third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
diff --git a/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp b/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
index c7685babd45c0dc954c0a852c454b8367de70065..a9133111dd5d151aa9bfcde0de79bff7e8aab72b 100644
--- a/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
+++ b/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
@@ -705,6 +705,21 @@ void MediaControls::onTimeUpdate() {
     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());