Fix test example in threading_and_tasks.md

It should be TEST_F since it uses a test fixture.

Change-Id: Ib81a04c656d57b3ff1cf3594cc8c8d62e4adfcab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3965462
Auto-Submit: Xiaohan Wang <[email protected]>
Commit-Queue: Xiaohan Wang <[email protected]>
Reviewed-by: Gabriel Charette <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1061272}
diff --git a/docs/threading_and_tasks.md b/docs/threading_and_tasks.md
index 71f75eb..b6852f4 100644
--- a/docs/threading_and_tasks.md
+++ b/docs/threading_and_tasks.md
@@ -728,7 +728,7 @@
    base::test::TaskEnvironment task_environment_;
 };
 
-TEST(MyTest, MyTest) {
+TEST_F(MyTest, FirstTest) {
   base::SingleThreadTaskRunner::GetCurrentDefault()->PostTask(FROM_HERE, base::BindOnce(&A));
   base::SequencedTaskRunner::GetCurrentDefault()->PostTask(FROM_HERE,
                                                    base::BindOnce(&B));