Check whether ScriptResource is still loading due to revalidation

third_party/WebKit/Source/core/loader/resource/ScriptResource.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
@@ skipping 65 matching lines @@
 void ScriptResource::onMemoryDump(WebMemoryDumpLevelOfDetail levelOfDetail,
                                   WebProcessMemoryDump* memoryDump) const {
   Resource::onMemoryDump(levelOfDetail, memoryDump);
   const String name = getMemoryDumpName() + "/decoded_script";
   auto dump = memoryDump->createMemoryAllocatorDump(name);
   dump->addScalar("size", "bytes", m_script.charactersSizeInBytes());
   memoryDump->addSuballocation(
       dump->guid(), String(WTF::Partitions::kAllocatedObjectPoolName));
 }
 
-const String& ScriptResource::script() {
-  DCHECK(isLoaded());
+NOINLINE const String& ScriptResource::script() {
+  // For investigating https://crbug.com/692856.
+  CHECK(isLoaded() || (isLoading() && hasRevalidated()));
+  CHECK(isLoaded() || (isLoading() && isCacheValidator()));
+  CHECK(isLoaded());
 
   if (m_script.isNull() && data()) {
     String script = decodedText();
     clearData();
     setDecodedSize(script.charactersSizeInBytes());
     m_script = AtomicString(script);
   }
 
   return m_script;
 }
 
 void ScriptResource::destroyDecodedDataForFailedRevalidation() {
   m_script = AtomicString();
 }
 
 // static
 bool ScriptResource::mimeTypeAllowedByNosniff(
     const ResourceResponse& response) {
   return parseContentTypeOptionsHeader(response.httpHeaderField(
              HTTPNames::X_Content_Type_Options)) != ContentTypeOptionsNosniff ||
          MIMETypeRegistry::isSupportedJavaScriptMIMEType(
              response.httpContentType());
 }
 
 }  // namespace blink