SimpleCache: Fix race condition in simple_index_file_unittest

net/disk_cache/simple/simple_index_file_unittest.cc

Index: net/disk_cache/simple/simple_index_file_unittest.cc
diff --git a/net/disk_cache/simple/simple_index_file_unittest.cc b/net/disk_cache/simple/simple_index_file_unittest.cc
index ede04176c3ce28e4fd7c414015ea98effa72b67a..a2603d8b911387d2f90b33791d6972dda8129048 100644
--- a/net/disk_cache/simple/simple_index_file_unittest.cc
+++ b/net/disk_cache/simple/simple_index_file_unittest.cc
@@ -292,8 +292,8 @@ TEST_F(SimpleIndexFileTest, SimpleCacheUpgrade) {
   // thread after that.
   MessageLoopHelper helper;
   CallbackTest cb_shutdown(&helper, false);
-  cache_thread.task_runner()->PostTask(
-      FROM_HERE,
+  cache_thread.task_runner()->PostTaskAndReply(
+      FROM_HERE, base::Bind(&base::DoNothing),
       base::Bind(&CallbackTest::Run, base::Unretained(&cb_shutdown), net::OK));
   helper.WaitUntilCacheIoFinished(1);