Add more string_util functions to base namespace.

extensions/browser/value_store/leveldb_value_store.cc

Index: extensions/browser/value_store/leveldb_value_store.cc
diff --git a/extensions/browser/value_store/leveldb_value_store.cc b/extensions/browser/value_store/leveldb_value_store.cc
index d29bc7477b1285e85abfc6cd506e60929a4f2a7c..0db63a17fcc4f6bdd00a34e07025ae98e8e8a6e0 100644
--- a/extensions/browser/value_store/leveldb_value_store.cc
+++ b/extensions/browser/value_store/leveldb_value_store.cc
@@ -435,7 +435,8 @@ scoped_ptr<ValueStore::Error> LeveldbValueStore::ToValueStoreError(
   std::string message = status.ToString();
   // The message may contain |db_path_|, which may be considered sensitive
   // data, and those strings are passed to the extension, so strip it out.
-  ReplaceSubstringsAfterOffset(&message, 0u, db_path_.AsUTF8Unsafe(), "...");
+  base::ReplaceSubstringsAfterOffset(
+      &message, 0u, db_path_.AsUTF8Unsafe(), "...");
 
   return Error::Create(CORRUPTION, message, key.Pass());
 }