FrameView: Don't try to update the throttling status of a deleted frame

third_party/WebKit/Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 291 matching lines @@
   // if the document has no content we can falsely think the frame is invisible.
   // Note that this means we cannot throttle top-level frames or (currently)
   // frames whose owner element is remote.
   Element* targetElement = frame().deprecatedLocalOwner();
   if (!targetElement)
     return;
 
   m_visibilityObserver = new ElementVisibilityObserver(
       targetElement, WTF::bind(
                          [](FrameView* frameView, bool isVisible) {
+                           if (!frameView)
+                             return;
                            frameView->updateRenderThrottlingStatus(
                                !isVisible, frameView->m_subtreeThrottled);
                            frameView->maybeRecordLoadReason();
                          },
                          wrapWeakPersistent(this)));
   m_visibilityObserver->start();
 }
 
 void FrameView::dispose() {
   RELEASE_ASSERT(!isInPerformLayout());
@@ skipping 4376 matching lines @@
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.width();
 }
 
 int FrameView::initialViewportHeight() const {
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.height();
 }
 
 }  // namespace blink