Backport some tests in...

Backport some tests in /components/password_manager/core/browser/android_affiliation to SingleThreadTaskEnvironment

These tests were previously migrated from single-threaded MessageLoop to
a multi-threaded TaskEnvironment (then named ScopedTaskEnvironment) as
part of crbug.com/891670.

//base OWNERS decided in retrospect that it was better to keep a
single-threaded option for TaskEnvironment and introduced
SingleThreadTaskEnvironment. This CL retrofits that decision for
/components/password_manager/core/browser/android_affiliation.

This CL is a no-op if it passes CQ.

This CL was uploaded by git cl split.

R=engedy@chromium.org

Bug: 891670
Change-Id: Ia5d73069ba593026184db80de535de0090617c86
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1786997
Auto-Submit: Gabriel Charette <gab@chromium.org>
Reviewed-by: Balazs Engedy <engedy@chromium.org>
Commit-Queue: Balazs Engedy <engedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#694241}

components/password_manager/core/browser/android_affiliation/affiliated_match_helper_unittest.cc

@@ -348,7 +348,7 @@ class AffiliatedMatchHelperTest : public testing::Test {
     RunUntilIdle();
   }
 
-  base::test::TaskEnvironment task_environment_;
+  base::test::SingleThreadTaskEnvironment task_environment_;
   base::ScopedMockTimeMessageLoopTaskRunner mock_time_task_runner_;
 
   std::vector<std::string> last_result_realms_;