Add a UseCounter for HTMLMediaElement.controller

Source/core/html/HTMLMediaElement.cpp

Index: Source/core/html/HTMLMediaElement.cpp
diff --git a/Source/core/html/HTMLMediaElement.cpp b/Source/core/html/HTMLMediaElement.cpp
index 598583eff9d79b8a11288cebdcca901165fbed4a..b2489f093d06fbbb873756b6077feec74a69e1aa 100644
--- a/Source/core/html/HTMLMediaElement.cpp
+++ b/Source/core/html/HTMLMediaElement.cpp
@@ -3841,8 +3841,10 @@ void HTMLMediaElement::setControllerInternal(PassRefPtr<MediaController> control
 
     m_mediaController = controller;
 
-    if (m_mediaController)
+    if (m_mediaController) {
+        UseCounter::count(document(), UseCounter::HTMLMediaElementControllerNotNull);
         m_mediaController->addMediaElement(this);
+    }
 
     if (hasMediaControls())
         mediaControls()->setMediaController(m_mediaController ? m_mediaController.get() : static_cast<MediaControllerInterface*>(this));