Fix a crash in the history publisher. This is caused by me changing the...

chrome/browser/history/history_publisher_win.cc

 // Copyright (c) 2008-2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/history/history_publisher.h"
 
 #include <atlsafe.h>
 #include <objbase.h>
 #include <oleauto.h>
 #include <wtypes.h>
@@ skipping 102 matching lines @@
   if (page_data.thumbnail) {
     for (size_t i = 0; i < page_data.thumbnail->size(); ++i)
       thumbnail_arr.Add((*page_data.thumbnail)[i]);
   }
 
   // Send data to registered indexers.
   ScopedVariant time(var_time, VT_DATE);
   ScopedBstr url(ASCIIToWide(page_data.url.spec()).c_str());
   ScopedBstr html(page_data.html);
   ScopedBstr title(page_data.title);
-  ScopedBstr format(ASCIIToWide(page_data.thumbnail_format).c_str());
+  // Don't send a NULL string through ASCIIToWide.
+  ScopedBstr format(page_data.thumbnail_format ?
+      ASCIIToWide(page_data.thumbnail_format).c_str() :
+      NULL);
   ScopedVariant psa(thumbnail_arr.m_psa);
   for (size_t i = 0; i < indexers_.size(); ++i) {
     indexers_[i]->SendPageData(time, url, html, title, format, psa);
   }
 }
 
 void HistoryPublisher::DeleteUserHistoryBetween(const base::Time& begin_time,
                                                 const base::Time& end_time)
     const {
   ScopedVariant var_begin_time(TimeToUTCVariantTime(begin_time), VT_DATE);
   ScopedVariant var_end_time(TimeToUTCVariantTime(end_time), VT_DATE);
   for (size_t i = 0; i < indexers_.size(); ++i) {
     indexers_[i]->DeleteUserHistoryBetween(var_begin_time, var_end_time);
   }
 }
 
 }  // namespace history