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

third_party/WebKit/Source/core/html/HTMLMediaElement.h

Index: third_party/WebKit/Source/core/html/HTMLMediaElement.h
diff --git a/third_party/WebKit/Source/core/html/HTMLMediaElement.h b/third_party/WebKit/Source/core/html/HTMLMediaElement.h
index 0bd98bca6d30fa8ac49f065ddad4b715583cedbb..b5fbef2d864e11db4478014d933be64688166492 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.h
@@ -504,6 +504,10 @@ class CORE_EXPORT HTMLMediaElement : public HTMLElement,
   // 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