Fix an AutoplayUmaHelper crash

third_party/WebKit/Source/core/html/AutoplayUmaHelper.h

 // 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.
 
 #ifndef AutoplayUmaHelper_h
 #define AutoplayUmaHelper_h
 
 #include "core/events/EventListener.h"
 #include "platform/heap/Handle.h"
 
@@ skipping 63 matching lines @@
     void maybeStopRecordingMutedVideoOffscreenDuration();
 
     void onVisibilityChangedForMutedVideoOffscreenDuration(bool isVisibile);
     void onVisibilityChangedForMutedVideoPlayMethodBecomeVisible(bool isVisible);
 
     bool shouldListenToUnloadEvent() const;
 
     // The autoplay source. Use AutoplaySource::NumberOfSources for invalid source.
     AutoplaySource m_source;
     // The media element this UMA helper is attached to. |m_element| owns |this|.
-    WeakMember<HTMLMediaElement> m_element;
+    Member<HTMLMediaElement> m_element;
 
     // The observer is used to observe whether a muted video autoplaying by play()
     // method become visible at some point.
     // The UMA is pending for recording as long as this observer is non-null.
     Member<ElementVisibilityObserver> m_mutedVideoPlayMethodVisibilityObserver;
 
     // -----------------------------------------------------------------------
     // Variables used for recording the duration of autoplay muted video playing offscreen.
     // The variables are valid when |m_autoplayOffscrenVisibilityObserver| is non-null.
     // The recording stops whenever the playback pauses or the page is unloaded.
 
     // The starting time of autoplaying muted video.
     int64_t m_mutedVideoAutoplayOffscreenStartTimeMS;
 
     // The duration an autoplaying muted video has been in offscreen.
     int64_t m_mutedVideoAutoplayOffscreenDurationMS;
 
     // Whether an autoplaying muted video is visible.
     bool m_isVisible;
 
     // The observer is used to observer an autoplaying muted video changing it's visibility,
     // which is used for offscreen duration UMA.
     // The UMA is pending for recording as long as this observer is non-null.
     Member<ElementVisibilityObserver> m_mutedVideoOffscreenDurationVisibilityObserver;
 };
 
 } // namespace blink
 
 #endif // AutoplayUmaHelper_h