Cleanup blink-side PlzNavigate logic

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2009 Adam Barth. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ skipping 478 matching lines @@
 void NavigationScheduler::schedule(ScheduledNavigation* redirect) {
   DCHECK(m_frame->page());
 
   // In a back/forward navigation, we sometimes restore history state to
   // iframes, even though the state was generated dynamically and JS will try to
   // put something different in the iframe. In this case, we will load stale
   // things and/or confuse the JS when it shortly thereafter tries to schedule a
   // location change. Let the JS have its way.
   // FIXME: This check seems out of place.
   if (!m_frame->loader().stateMachine()->committedFirstRealDocumentLoad() &&
-      m_frame->loader().provisionalDocumentLoader()) {
+      m_frame->loader().provisionalDocumentLoader() &&
+      m_frame->loader().provisionalDocumentLoader()->didStart()) {
     m_frame->loader().stopAllLoaders();
     if (!m_frame->host())
       return;
   }
 
   cancel();
   m_redirect = redirect;
   startTimer();
 }
 
@@ skipping 30 matching lines @@
   m_navigateTaskHandle.cancel();
   m_redirect.clear();
 }
 
 DEFINE_TRACE(NavigationScheduler) {
   visitor->trace(m_frame);
   visitor->trace(m_redirect);
 }
 
 }  // namespace blink