PlzNavigate: Clear provisional history item on redirects.

third_party/WebKit/Source/core/loader/FrameLoader.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) Research In Motion Limited 2009. 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:
  *
@@ skipping 139 matching lines @@
     Frame* opener();
     void setOpener(LocalFrame*);
 
     void detach();
 
     void finishedParsing();
     void checkCompleted();
 
     void receivedMainResourceRedirect(const KURL& newURL);
 
+    void discardProvisionalHistoryItem();
+
     // This prepares the FrameLoader for the next commit. It will dispatch
     // unload events, abort XHR requests and detach the document. Returns true
     // if the frame is ready to receive the next commit, or false otherwise.
     bool prepareForCommit();
 
     void commitProvisionalLoad();
 
     FrameLoaderStateMachine* stateMachine() const { return &m_stateMachine; }
 
     void applyUserAgent(ResourceRequest&);
@@ skipping 110 matching lines @@
 
     SandboxFlags m_forcedSandboxFlags;
 
     bool m_dispatchingDidClearWindowObjectInMainWorld;
     bool m_protectProvisionalLoader;
 };
 
 } // namespace blink
 
 #endif // FrameLoader_h