Fix an AutoplayUmaHelper crash

third_party/WebKit/Source/core/html/AutoplayUmaHelper.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 "core/html/AutoplayUmaHelper.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/ElementVisibilityObserver.h"
 #include "core/events/Event.h"
 #include "core/frame/LocalDOMWindow.h"
@@ skipping 80 matching lines @@
     autoplayUnmuteHistogram.count(static_cast<int>(status));
 }
 
 void AutoplayUmaHelper::didMoveToNewDocument(Document& oldDocument)
 {
     if (!shouldListenToUnloadEvent())
         return;
 
     if (oldDocument.domWindow())
         oldDocument.domWindow()->removeEventListener(EventTypeNames::unload, this, false);
-    if (m_element && m_element->document().domWindow())
+    if (m_element->document().domWindow())
         m_element->document().domWindow()->addEventListener(EventTypeNames::unload, this, false);
 }
 
 void AutoplayUmaHelper::onVisibilityChangedForMutedVideoPlayMethodBecomeVisible(bool isVisible)
 {
     if (!isVisible || !m_mutedVideoPlayMethodVisibilityObserver)
         return;
 
     maybeStopRecordingMutedVideoPlayMethodBecomeVisible(true);
 }
@@ skipping 101 matching lines @@
     }
     m_mutedVideoOffscreenDurationVisibilityObserver->stop();
     m_mutedVideoOffscreenDurationVisibilityObserver = nullptr;
     m_mutedVideoAutoplayOffscreenDurationMS = 0;
     m_element->removeEventListener(EventTypeNames::pause, this, false);
     maybeUnregisterUnloadListener();
 }
 
 void AutoplayUmaHelper::maybeUnregisterUnloadListener()
 {
-    if (!shouldListenToUnloadEvent() && m_element && m_element->document().domWindow())
+    if (!shouldListenToUnloadEvent() && m_element->document().domWindow())
         m_element->document().domWindow()->removeEventListener(EventTypeNames::unload, this, false);
 }
 
 bool AutoplayUmaHelper::shouldListenToUnloadEvent() const
 {
     return m_mutedVideoPlayMethodVisibilityObserver || m_mutedVideoOffscreenDurationVisibilityObserver;
 }
 
 DEFINE_TRACE(AutoplayUmaHelper)
 {
     EventListener::trace(visitor);
     visitor->trace(m_element);
     visitor->trace(m_mutedVideoPlayMethodVisibilityObserver);
     visitor->trace(m_mutedVideoOffscreenDurationVisibilityObserver);
 }
 
 } // namespace blink