Update autoplay settings when moving media elements between documents

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

Index: third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
index 7beecb9dd4be9a28665ac847fe9e6f45f67b085f..897f538769f9fd7766a109fddb8e0c879802bbc2 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
@@ -487,6 +487,13 @@ void HTMLMediaElement::didMoveToNewDocument(Document& oldDocument)
 {
     DVLOG(MEDIA_LOG_LEVEL) << "didMoveToNewDocument(" << (void*)this << ")";
 
+    // If any experiment is enabled, then we want to enable a user gesture by
+    // default, otherwise the experiment does nothing.
+    if ((document().settings() && document().settings()->mediaPlaybackRequiresUserGesture())
+        || m_autoplayHelper->isExperimentEnabled()) {

[mlamouri (slow - plz ping), 2016/06/07 15:40:28]

I think you should do something like:
```
bool oldDocumentRequiresUserGesture = <what you did but for the old document>
bool newDocumentRequiresUserGesture = <what you did>
if (newDocumentRequiresUserGesture && !oldDocumentRequiresUserGesture)
    m_lockedPendingUserGesture = true;
```

I'm afraid what you wrote here would re-set to true the lock after the document
move regardless of the context.

[Zhiqiang Zhang (Slow), 2016/06/07 17:02:40]

Done.

+        m_lockedPendingUserGesture = true;
+    }
+
     if (m_shouldDelayLoadEvent) {
         document().incrementLoadEventDelayCount();
         // Note: Keeping the load event delay count increment on oldDocument that was added