PlzNavigate: Clear provisional history item on redirects.

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 190 matching lines @@
         break;
     default:
         ASSERT_NOT_REACHED();
     }
 
     if (resource)
         fetcher()->preloadStarted(resource);
     return resource;
 }
 
+void DocumentLoader::discardProvisionalHistoryItem()
+{
+    FrameLoader* frameloader = frameLoader();
+    if (frameloader)
+        frameloader->discardProvisionalHistoryItem();
+}
+
 void DocumentLoader::dispatchLinkHeaderPreloads(ViewportDescriptionWrapper* viewport, LinkLoader::MediaPreloadPolicy mediaPolicy)
 {
     LinkLoader::loadLinksFromHeader(response().httpHeaderField(HTTPNames::Link), response().url(), m_frame->document(), NetworkHintsInterfaceImpl(), LinkLoader::OnlyLoadResources, mediaPolicy, viewport);
 }
 
 void DocumentLoader::didChangePerformanceTiming()
 {
     if (frame() && frame()->isMainFrame() && m_state >= Committed) {
         frameLoader()->client()->didChangePerformanceTiming();
     }
@@ skipping 494 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