Media: fix memory leak because of the document holding on an EventListener.

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "MediaControlsOrientationLockDelegate.h"
 
 #include "core/events/Event.h"
 #include "core/frame/ScreenOrientationController.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/page/ChromeClient.h"
@@ skipping 46 matching lines @@
  public:
   void onSuccess() override {}
   void onError(WebLockOrientationError) override {}
 };
 
 }  // anonymous namespace
 
 MediaControlsOrientationLockDelegate::MediaControlsOrientationLockDelegate(
     HTMLVideoElement& video)
     : EventListener(CPPEventListenerType), m_videoElement(video) {
+  if (videoElement().isConnected())
+    attach();
+}
+
+void MediaControlsOrientationLockDelegate::attach() {
   document().addEventListener(EventTypeNames::fullscreenchange, this, true);
   videoElement().addEventListener(EventTypeNames::webkitfullscreenchange, this,
                                   true);
   videoElement().addEventListener(EventTypeNames::loadedmetadata, this, true);
 }
 
+void MediaControlsOrientationLockDelegate::detach() {
+  document().removeEventListener(EventTypeNames::fullscreenchange, this, true);
+  videoElement().removeEventListener(EventTypeNames::webkitfullscreenchange,
+                                     this, true);
+  videoElement().removeEventListener(EventTypeNames::loadedmetadata, this,
+                                     true);
+}
+
 bool MediaControlsOrientationLockDelegate::operator==(
     const EventListener& other) const {
   return this == &other;
 }
 
 void MediaControlsOrientationLockDelegate::maybeLockOrientation() {
   DCHECK(m_state != State::MaybeLockedFullscreen);
 
   if (videoElement().getReadyState() == HTMLMediaElement::kHaveNothing) {
     recordMetadataAvailability(MetadataAvailabilityMetrics::Missing);
@@ skipping 109 matching lines @@
   NOTREACHED();
   return WebScreenOrientationLockLandscape;
 }
 
 DEFINE_TRACE(MediaControlsOrientationLockDelegate) {
   EventListener::trace(visitor);
   visitor->trace(m_videoElement);
 }
 
 }  // namespace blink