Nothing is ever added to hosts_to_delete_, so this code does nothing useful.

chrome/browser/search_engines/template_url_model.h

Index: chrome/browser/search_engines/template_url_model.h
diff --git a/chrome/browser/search_engines/template_url_model.h b/chrome/browser/search_engines/template_url_model.h
index add796a642893b60b5245437bf3b3e3e2ea8a6ca..c8ad1e3aec36c419b170a3c1250b3a79ac743326 100644
--- a/chrome/browser/search_engines/template_url_model.h
+++ b/chrome/browser/search_engines/template_url_model.h
@@ -365,13 +365,6 @@ class TemplateURLModel : public WebDataServiceConsumer,
   // Service used to store entries.
   scoped_refptr<WebDataService> service_;
 
-  // List of hosts to feed to DeleteGeneratedKeywordsMatchingHost. When
-  // we receive NOTIFY_HOST_DELETED_FROM_HISTORY if we haven't loaded yet,
-  // we force a load and add the host to hosts_to_delete_. When done loading
-  // we invoke DeleteGeneratedKeywordsMatchingHost with all the elements of
-  // the vector.
-  std::vector<std::wstring> hosts_to_delete_;
-
   // All visits that occurred before we finished loading. Once loaded
   // UpdateKeywordSearchTermsForURL is invoked for each element of the vector.
   std::vector<history::URLVisitedDetails> visits_to_add_;