Media Controls: do not use events but C++ callbacks for insertion/removal from document.

third_party/WebKit/Source/core/html/shadow/MediaControlsOrientationLockDelegate.cpp

Index: third_party/WebKit/Source/core/html/shadow/MediaControlsOrientationLockDelegate.cpp
diff --git a/third_party/WebKit/Source/core/html/shadow/MediaControlsOrientationLockDelegate.cpp b/third_party/WebKit/Source/core/html/shadow/MediaControlsOrientationLockDelegate.cpp
index f29c4c5e96961e78a9d3f10d87f856742bdb2348..71d89b35e4e776ac71a0738f96e19a9387791acd 100644
--- a/third_party/WebKit/Source/core/html/shadow/MediaControlsOrientationLockDelegate.cpp
+++ b/third_party/WebKit/Source/core/html/shadow/MediaControlsOrientationLockDelegate.cpp
@@ -69,6 +69,8 @@ MediaControlsOrientationLockDelegate::MediaControlsOrientationLockDelegate(
 }
 
 void MediaControlsOrientationLockDelegate::attach() {
+  DCHECK(videoElement().isConnected());
+
   document().addEventListener(EventTypeNames::fullscreenchange, this, true);
   videoElement().addEventListener(EventTypeNames::webkitfullscreenchange, this,
                                   true);
@@ -76,6 +78,8 @@ void MediaControlsOrientationLockDelegate::attach() {
 }
 
 void MediaControlsOrientationLockDelegate::detach() {
+  DCHECK(!videoElement().isConnected());
+
   document().removeEventListener(EventTypeNames::fullscreenchange, this, true);
   videoElement().removeEventListener(EventTypeNames::webkitfullscreenchange,
                                      this, true);