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 e6e83de80c7d6ba991bc7befd8f67045fe532b17..b72d17d53551adfcc9b58d6501a234a8c6442017 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
@@ -428,8 +428,12 @@ 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, else the experiment does nothing.

[philipj_slow, 2016/04/05 11:17:51]

s/else/otherwise/

[liberato (no reviews please), 2016/04/25 22:38:44]

Done.

+    if ((document.settings() && document.settings()->mediaPlaybackRequiresUserGesture())

[philipj_slow, 2016/04/05 11:17:51]

Can't the same code that enables the experiment also set this setting?

[mlamouri (slow - plz ping), 2016/04/21 17:11:35]

They are fairly close:
https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/r...

[liberato (no reviews please), 2016/04/25 22:38:44]

in PS{2,3}, i've left it as-is to avoid parsing the experiment string.

if either of you feel strongly, please let me know and i'll move it.

[liberato (no reviews please), 2016/04/25 22:38:44]

the experiment is enabled by copying the string around, until it ends up in
blink::Settings::autoplayExperimentMode.  nothing attempts to interpret it;
that's all done in HTMLMediaElement.

that's why i just override in the element.  it keeps the interpretation of the
string centralized.

+        || m_autoplayHelper->isExperimentEnabled()) {
         m_userGestureRequiredForPlay = true;
+    }
 
     setHasCustomStyleCallbacks();
     addElementToDocumentMap(this, &document);