PlzNavigate: fix crash when updating redirect timing.

third_party/WebKit/Source/web/WebDataSourceImpl.cpp

 /*
  * Copyright (C) 2009 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 57 matching lines @@
 
 void WebDataSourceImpl::appendRedirect(const WebURL& url) {
   DocumentLoader::appendRedirect(url);
 }
 
 void WebDataSourceImpl::updateNavigation(
     double redirectStartTime,
     double redirectEndTime,
     double fetchStartTime,
     const WebVector<WebURL>& redirectChain) {
-  for (size_t i = 0; i + 1 < redirectChain.size(); ++i)
-    didRedirect(redirectChain[i], redirectChain[i + 1]);
-  timing().setRedirectStart(redirectStartTime);
-  timing().setRedirectEnd(redirectEndTime);
+  // Updates the redirection timing if there is at least one redirection
+  // (between two URLs).
+  if (redirectChain.size() >= 2) {
+    for (size_t i = 0; i + 1 < redirectChain.size(); ++i)
+      didRedirect(redirectChain[i], redirectChain[i + 1]);
+    timing().setRedirectStart(redirectStartTime);
+    timing().setRedirectEnd(redirectEndTime);
+  }
   timing().setFetchStart(fetchStartTime);
 }
 
 void WebDataSourceImpl::redirectChain(WebVector<WebURL>& result) const {
   result.assign(m_redirectChain);
 }
 
 bool WebDataSourceImpl::isClientRedirect() const {
   return DocumentLoader::isClientRedirect();
 }
@@ skipping 59 matching lines @@
 void WebDataSourceImpl::setSubresourceFilter(
     WebDocumentSubresourceFilter* subresourceFilter) {
   DocumentLoader::setSubresourceFilter(WTF::wrapUnique(subresourceFilter));
 }
 
 DEFINE_TRACE(WebDataSourceImpl) {
   DocumentLoader::trace(visitor);
 }
 
 }  // namespace blink