Fix a crash when setting MediaControlsEnabled setting for videos without controls

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 363 matching lines @@
 }
 
 void HTMLMediaElement::onMediaControlsEnabledChange(Document* document) {
   auto it = documentToElementSetMap().find(document);
   if (it == documentToElementSetMap().end())
     return;
   DCHECK(it->value);
   WeakMediaElementSet& elements = *it->value;
   for (const auto& element : elements) {
     element->updateControlsVisibility();
-    element->mediaControls()->onMediaControlsEnabledChange();
+    if (element->mediaControls())
+      element->mediaControls()->onMediaControlsEnabledChange();
   }
 }
 
 HTMLMediaElement::HTMLMediaElement(const QualifiedName& tagName,
                                    Document& document)
     : HTMLElement(tagName, document),
       SuspendableObject(&document),
       m_loadTimer(TaskRunnerHelper::get(TaskType::Unthrottled, &document),
                   this,
                   &HTMLMediaElement::loadTimerFired),
@@ skipping 3774 matching lines @@
       kMostlyFillViewportBecomeStableSeconds, BLINK_FROM_HERE);
 }
 
 void HTMLMediaElement::viewportFillDebouncerTimerFired(TimerBase*) {
   m_mostlyFillingViewport = true;
   if (m_webMediaPlayer)
     m_webMediaPlayer->becameDominantVisibleContent(m_mostlyFillingViewport);
 }
 
 }  // namespace blink