Replace "nested message loop" with "nested run loop" in comments.

third_party/WebKit/Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
@@ skipping 2493 matching lines @@
 void Document::Shutdown() {
   TRACE_EVENT0("blink", "Document::shutdown");
   CHECK(!frame_ || frame_->Tree().ChildCount() == 0);
   if (!IsActive())
     return;
 
   // Frame navigation can cause a new Document to be attached. Don't allow that,
   // since that will cause a situation where LocalFrame still has a Document
   // attached after this finishes!  Normally, it shouldn't actually be possible
   // to trigger navigation here.  However, plugins (see below) can cause lots of
-  // crazy things to happen, since plugin detach involves nested message loops.
+  // crazy things to happen, since plugin detach involves nested run loops.
   FrameNavigationDisabler navigation_disabler(*frame_);
   // Defer FrameViewBase updates to avoid plugins trying to run script inside
   // ScriptForbiddenScope, which will crash the renderer after
   // https://crrev.com/200984
   HTMLFrameOwnerElement::UpdateSuspendScope
       suspend_frame_view_base_hierarchy_updates;
   // Don't allow script to run in the middle of detachLayoutTree() because a
   // detaching Document is not in a consistent state.
   ScriptForbiddenScope forbid_script;
 
@@ skipping 4256 matching lines @@
 }
 
 void showLiveDocumentInstances() {
   WeakDocumentSet& set = liveDocumentSet();
   fprintf(stderr, "There are %u documents currently alive:\n", set.size());
   for (blink::Document* document : set)
     fprintf(stderr, "- Document %p URL: %s\n", document,
             document->Url().GetString().Utf8().data());
 }
 #endif