ASSERT -> {DCHECK|DCHECK_XX}, ENABLE(ASSERT) -> DCHECK_IS_ON() in dom

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

 // Copyright 2015 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/dom/DocumentVisibilityObserver.h"
 
 #include "core/dom/Document.h"
 
 namespace blink {
 
@@ skipping 18 matching lines @@
 void DocumentVisibilityObserver::unregisterObserver()
 {
     if (m_document) {
         m_document->unregisterVisibilityObserver(this);
         m_document = nullptr;
     }
 }
 
 void DocumentVisibilityObserver::registerObserver(Document& document)
 {
-    ASSERT(!m_document);
+    DCHECK(!m_document);
     m_document = &document;
     if (m_document)
         m_document->registerVisibilityObserver(this);
 }
 
 void DocumentVisibilityObserver::setObservedDocument(Document& document)
 {
     unregisterObserver();
     registerObserver(document);
 }
 
 } // namespace blink