docs: fix example parameter name in threading_and_tasks_testing

The parameter name passed to the DoSomethingAndReply example function
does not match the name of the callback given to PostTask.

Bug: none
Change-Id: I7899a22880adb0ea98f717e6415a3ce562853ef6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2121349
Auto-Submit: Trent Begin <[email protected]>
Reviewed-by: Gabriel Charette <[email protected]>
Commit-Queue: Gabriel Charette <[email protected]>
Cr-Commit-Position: refs/heads/master@{#753423}
diff --git a/docs/threading_and_tasks_testing.md b/docs/threading_and_tasks_testing.md
index 1ab22e3..5110be1 100644
--- a/docs/threading_and_tasks_testing.md
+++ b/docs/threading_and_tasks_testing.md
@@ -54,7 +54,7 @@
  public:
   Foo() : owning_sequence_(base::SequencedTaskRunnerHandle::Get()) {}
 
-  DoSomethingAndReply(base::OnceClosure reply) {
+  DoSomethingAndReply(base::OnceClosure on_done) {
     DCHECK(owning_sequence_->RunsTasksInCurrentSequence());
     something_was_done_ = true;
     owning_sequence_->PostTask(on_done);