DocumentLoader::isCommittedButEmpty is timing-dependent.

Source/core/loader/DocumentLoader.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 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 86 matching lines @@
     void updateForSameDocumentNavigation(const KURL&, SameDocumentNavigationSource);
     void stopLoading();
     bool isLoading() const;
     const ResourceResponse& response() const { return m_response; }
     const ResourceError& mainDocumentError() const { return m_mainDocumentError; }
     bool isClientRedirect() const { return m_isClientRedirect; }
     void setIsClientRedirect(bool isClientRedirect) { m_isClientRedirect = isClientRedirect; }
     bool replacesCurrentHistoryItem() const { return m_replacesCurrentHistoryItem; }
     void setReplacesCurrentHistoryItem(bool replacesCurrentHistoryItem) { m_replacesCurrentHistoryItem = replacesCurrentHistoryItem; }
 
-    bool isCommittedButEmpty() const { return m_state == Committed; }
+    bool isCommittedButEmpty() const { return m_state == Committed || m_state == MainResourceDoneEmpty; }
 
     bool shouldContinueForNavigationPolicy(const ResourceRequest&, ContentSecurityPolicyDisposition shouldCheckMainWorldContentSecurityPolicy, NavigationPolicy = NavigationPolicyCurrentTab);
     NavigationType navigationType() const { return m_navigationType; }
     void setNavigationType(NavigationType navigationType) { m_navigationType = navigationType; }
 
     void setDefersLoading(bool);
 
     void startLoadingMainResource();
     void cancelMainResourceLoad(const ResourceError&);
 
@@ skipping 109 matching lines @@
 
     RefPtrWillBeMember<ContentSecurityPolicy> m_contentSecurityPolicy;
     ClientHintsPreferences m_clientHintsPreferences;
     InitialScrollState m_initialScrollState;
 
     enum State {
         NotStarted,
         Provisional,
         Committed,
         DataReceived,
-        MainResourceDone
+        MainResourceDone,
+        MainResourceDoneEmpty

[dcheng, 2015/09/21 16:43:52]

Would it make sense to call this "DoneButEmpty" to match the "CommittedButEmpty"
name earlier?

[Nate Chapin, 2015/09/21 16:45:30]

Yeah, probably. Will update before landing.

     };
     State m_state;
 
     // Used to protect against reentrancy into dataReceived().
     bool m_inDataReceived;
     RefPtr<SharedBuffer> m_dataBuffer;
 };
 
 DECLARE_WEAK_IDENTIFIER_MAP(DocumentLoader);
 
 } // namespace blink
 
 #endif // DocumentLoader_h