Replace uses of hash_map in //base

base/stl_util.h

Index: base/stl_util.h
diff --git a/base/stl_util.h b/base/stl_util.h
index 5a9b7b80a4966b4f5d10d58ab9f47b551c98bb43..05b69a75811ace240def80abfda6c748d92ddb18 100644
--- a/base/stl_util.h
+++ b/base/stl_util.h
@@ -76,7 +76,7 @@ inline char* string_as_array(std::string* str) {
   return str->empty() ? NULL : &*str->begin();
 }
 
-// Test to see if a set, map, hash_set or hash_map contains a particular key.
+// Test to see if a set or map contains a particular key.
 // Returns true if the key is in the collection.
 template <typename Collection, typename Key>
 bool ContainsKey(const Collection& collection, const Key& key) {