DocumentLoader::isCommittedButEmpty is timing-dependent.

third_party/WebKit/Source/core/loader/DocumentLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Google 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.
@@ skipping 87 matching lines @@
 }
 
 DocumentLoader::DocumentLoader(LocalFrame* frame, const ResourceRequest& req, const SubstituteData& substituteData)
     : m_frame(frame)
     , m_fetcher(FrameFetchContext::createContextAndFetcher(this, nullptr))
     , m_originalRequest(req)
     , m_substituteData(substituteData)
     , m_request(req)
     , m_isClientRedirect(false)
     , m_replacesCurrentHistoryItem(false)
+    , m_dataReceived(false)
     , m_navigationType(NavigationTypeOther)
     , m_documentLoadTiming(*this)
     , m_timeOfLastDataReceived(0.0)
     , m_applicationCacheHost(ApplicationCacheHost::create(this))
     , m_wasBlockedAfterXFrameOptionsOrCSP(false)
     , m_state(NotStarted)
     , m_inDataReceived(false)
     , m_dataBuffer(SharedBuffer::create())
 {
 }
@@ skipping 362 matching lines @@
 {
     ASSERT(m_state < MainResourceDone);
     ensureWriter(m_response.mimeType());
 
     // This can happen if document.close() is called by an event handler while
     // there's still pending incoming data.
     if (m_frame && !m_frame->document()->parsing())
         return;
 
     if (length)
-        m_state = DataReceived;
+        m_dataReceived = true;
 
     m_writer->addData(bytes, length);
 }
 
 void DocumentLoader::dataReceived(Resource* resource, const char* data, size_t length)
 {
     ASSERT(data);
     ASSERT(length);
     ASSERT_UNUSED(resource, resource == m_mainResource);
     ASSERT(!m_response.isNull());
@@ skipping 209 matching lines @@
 {
     m_writer = createWriterFor(init, mimeType(), m_writer ? m_writer->encoding() : emptyAtom, true, ForceSynchronousParsing);
     if (!source.isNull())
         m_writer->appendReplacingData(source);
     endWriting(m_writer.get());
 }
 
 DEFINE_WEAK_IDENTIFIER_MAP(DocumentLoader);
 
 } // namespace blink