Gender-neutralize a few more comments / strings.

components/omnibox/browser/in_memory_url_index.cc

Index: components/omnibox/browser/in_memory_url_index.cc
diff --git a/components/omnibox/browser/in_memory_url_index.cc b/components/omnibox/browser/in_memory_url_index.cc
index f8c8d3a7ceafaa568c1a34fda5452d191b205ce7..1e0eed1221b7493f373b4f43576226add543d904 100644
--- a/components/omnibox/browser/in_memory_url_index.cc
+++ b/components/omnibox/browser/in_memory_url_index.cc
@@ -177,7 +177,7 @@ void InMemoryURLIndex::OnURLsDeleted(history::HistoryService* history_service,
   // through an unclean shutdown (and therefore fail to write a new cache file),
   // when Chrome restarts and we restore from the previous cache, we'll end up
   // searching over URLs that may be deleted.  This would be wrong, and
-  // surprising to the user who bothered to delete some URLs from his/her
+  // surprising to the user who bothered to delete some URLs from their
   // history.  In this situation, deleting the cache is a better solution than
   // writing a new cache (after deleting the URLs from the in-memory structure)
   // because deleting the cache forces it to be rebuilt from history upon