Cleaning up url_index_private_data and in_memory_url_index_types.

components/omnibox/browser/url_index_private_data.h

Index: components/omnibox/browser/url_index_private_data.h
diff --git a/components/omnibox/browser/url_index_private_data.h b/components/omnibox/browser/url_index_private_data.h
index 50bcf4b7ebc141548414f53a4b833f35de5717db..789057aabbbac1c139324b7e76acb0bbf0ad36d1 100644
--- a/components/omnibox/browser/url_index_private_data.h
+++ b/components/omnibox/browser/url_index_private_data.h
@@ -8,6 +8,7 @@
 #include <stddef.h>
 
 #include <set>
+#include <stack>
 #include <string>
 
 #include "base/files/file_path.h"
@@ -253,17 +254,9 @@ class URLIndexPrivateData
   // history item identified by |history_id| to the index.
   void AddWordToIndex(const base::string16& uni_word, HistoryID history_id);
 
-  // Creates a new entry in the word/history map for |word_id| and add
-  // |history_id| as the initial element of the word's set.
-  void AddWordHistory(const base::string16& uni_word, HistoryID history_id);
-
-  // Updates an existing entry in the word/history index by adding the
-  // |history_id| to set for |word_id| in the word_id_history_map_.
-  void UpdateWordHistory(WordID word_id, HistoryID history_id);
-
-  // Adds |word_id| to |history_id|'s entry in the history/word map,
-  // creating a new entry if one does not already exist.
-  void AddToHistoryIDWordMap(HistoryID history_id, WordID word_id);
+  // Adds a new entry to word_list. Uses previously freed positions if
+  // available.
+  WordID AddNewWordToWordList(const base::string16& term);
 
   // Removes |row| and all associated words and characters from the index.
   void RemoveRowFromIndex(const history::URLRow& row);
@@ -346,7 +339,7 @@ class URLIndexPrivateData
   // modified or deleted old words may be removed from the index, in which
   // case the slots for those words are added to available_words_ for resuse
   // by future URL updates.
-  WordIDSet available_words_;
+  std::stack<WordID> available_words_;
 
   // A one-to-one mapping from the a word string to its slot number (i.e.
   // WordID) in the |word_list_|.