Fix use-after-move in //chrome/services/machine_learning/public/cpp/test_support/

Fix use-after-move (potential) bugs found by the
"bugprone-use-after-move" clang-tidy check.

Bug: 1122844
Change-Id: Ib8f4ae6bb906363dbbab8ed1157a78b3e6a0e4bf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2383015Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Commit-Queue: Maksim Ivanov <emaxx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#802903}

chrome/services/machine_learning/public/cpp/test_support/fake_service_connection.cc

@@ -27,6 +27,7 @@ FakeServiceConnection::~FakeServiceConnection() {
 void FakeServiceConnection::ScheduleCall(base::OnceClosure callback) {
   if (!is_async_) {
     std::move(callback).Run();
+    return;
   }
 
   pending_calls_.emplace_back(std::move(callback));