Adding an experimental flag to block autoplay with sound in cross-origin iframes

third_party/WebKit/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:
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@@ skipping 486 matching lines @@
   // WebMemediaPlayer objects advertise they have audio and/or video, but don't
   // explicitly signal them via addAudioTrack() and addVideoTrack().
   // FIXME: Remove this once all WebMediaPlayer implementations properly report
   // their track info.
   void createPlaceholderTracksIfNecessary();
 
   // Sets the selected/enabled tracks if they aren't set before we initially
   // transition to kHaveMetadata.
   void selectInitialTracksIfNecessary();
 
+  // Return true if and only if |m_lockedPendingUserGesture| should be
+  // initialized as true.

[mlamouri (slow - plz ping), 2016/11/18 14:33:10]

The comment isn't entirely true because otherwise you could have a
`resetLockedPendingUserGesture()`. Instead, it's whether the document settings
would require media playback to have a user gesture.

Can you add a TODO to move this to the anonymous namespace when
AutoplayExperiment is removed?

[Zhiqiang Zhang (Slow), 2016/11/21 18:06:23]

Done.

+  bool computeLockedPendingUserGesture(Document&) const;
+
   // Return true if and only if a user gesture is required to unlock this
   // media element for unrestricted autoplay / script control.  Don't confuse
   // this with isGestureNeededForPlayback().  The latter is usually what one
   // should use, if checking to see if an action is allowed.
   bool isLockedPendingUserGesture() const;
 
   // If the user gesture is required, then this will remove it.  Note that
   // one should not generally call this method directly; use the one on
   // m_helper and give it a reason.
   void unlockUserGesture();
@@ skipping 219 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