Enable user gesture requirement for autoplay experiment.

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 8beea08cbcdda8e7b55f8d57890f68315abf9bed..afcea26b5abf13f34f7beed38feb0d64132182b2 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
@@ -441,8 +441,12 @@ HTMLMediaElement::HTMLMediaElement(const QualifiedName& tagName, Document& docum
 
     WTF_LOG(Media, "HTMLMediaElement::HTMLMediaElement(%p)", this);
 
-    if (document.settings() && document.settings()->mediaPlaybackRequiresUserGesture())
+    // 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()) {
         m_userGestureRequiredForPlay = true;
+    }
 
     setHasCustomStyleCallbacks();
     addElementToDocumentMap(this, &document);