Reland 'Convert //net and //chromecast to std::unordered_*'

net/disk_cache/simple/simple_index.cc

Index: net/disk_cache/simple/simple_index.cc
diff --git a/net/disk_cache/simple/simple_index.cc b/net/disk_cache/simple/simple_index.cc
index 75c0af360cb3315bacf2785da94688dabccc034a..2d4c701ce27fa035402f21cd2c8d40f385951018 100644
--- a/net/disk_cache/simple/simple_index.cc
+++ b/net/disk_cache/simple/simple_index.cc
@@ -402,7 +402,8 @@ void SimpleIndex::MergeInitializingSet(
 
   EntrySet* index_file_entries = &load_result->entries;
 
-  for (base::hash_set<uint64_t>::const_iterator it = removed_entries_.begin();
+  for (std::unordered_set<uint64_t>::const_iterator it =
+           removed_entries_.begin();
        it != removed_entries_.end(); ++it) {
     index_file_entries->erase(*it);
   }