Switching to flat_sets in HQP.

components/omnibox/browser/in_memory_url_index_types.h

Index: components/omnibox/browser/in_memory_url_index_types.h
diff --git a/components/omnibox/browser/in_memory_url_index_types.h b/components/omnibox/browser/in_memory_url_index_types.h
index 6d38a79f9c7a001b762845cc38cc85175c77e5da..d3e656ca85c67169aeae28f39b3abe2a1fd151c9 100644
--- a/components/omnibox/browser/in_memory_url_index_types.h
+++ b/components/omnibox/browser/in_memory_url_index_types.h
@@ -8,9 +8,9 @@
 #include <stddef.h>
 
 #include <map>
-#include <set>
 #include <vector>
 
+#include "base/containers/flat_set.h"
 #include "base/containers/hash_tables.h"
 #include "base/strings/string16.h"
 #include "components/history/core/browser/history_types.h"
@@ -69,8 +69,8 @@ TermMatches ReplaceOffsetsInTermMatches(const TermMatches& matches,
 // Convenience Types -----------------------------------------------------------
 
 typedef std::vector<base::string16> String16Vector;
-typedef std::set<base::string16> String16Set;
-typedef std::set<base::char16> Char16Set;
+typedef base::flat_set<base::string16> String16Set;
+typedef base::flat_set<base::char16> Char16Set;
 typedef std::vector<base::char16> Char16Vector;
 
 // A vector that contains the offsets at which each word starts within a string.
@@ -131,12 +131,12 @@ typedef size_t WordID;
 typedef std::map<base::string16, WordID> WordMap;
 
 // A map from character to the word_ids of words containing that character.
-typedef std::set<WordID> WordIDSet;  // An index into the WordList.
+typedef base::flat_set<WordID> WordIDSet;  // An index into the WordList.
 typedef std::map<base::char16, WordIDSet> CharWordIDMap;
 
 // A map from word (by word_id) to history items containing that word.
 typedef history::URLID HistoryID;
-typedef std::set<HistoryID> HistoryIDSet;
+typedef base::flat_set<HistoryID> HistoryIDSet;
 typedef std::vector<HistoryID> HistoryIDVector;
 typedef std::map<WordID, HistoryIDSet> WordIDHistoryMap;
 typedef std::map<HistoryID, WordIDSet> HistoryIDWordMap;