Revert of Disallow posting tasks to SequencedWorkerPools by default.

base/threading/sequenced_worker_pool_unittest.cc

Index: base/threading/sequenced_worker_pool_unittest.cc
diff --git a/base/threading/sequenced_worker_pool_unittest.cc b/base/threading/sequenced_worker_pool_unittest.cc
index 39b424cdfc1402ed3c23624b8afd7c7e36c42cd4..d2007f8be52241628321b5d55766ce308f2a80ab 100644
--- a/base/threading/sequenced_worker_pool_unittest.cc
+++ b/base/threading/sequenced_worker_pool_unittest.cc
@@ -254,12 +254,8 @@
       TaskScheduler::CreateAndSetDefaultTaskScheduler(
           std::move(worker_pool_params),
           base::Bind([](const TaskTraits&) -> size_t { return 0U; }));
-
-      // Unit tests run in an environment where SequencedWorkerPool is enabled
-      // without redirection to TaskScheduler. For the current unit test,
-      // disable it and re-enable it with redirection to TaskScheduler.
-      SequencedWorkerPool::DisableForProcessForTesting();
-      SequencedWorkerPool::EnableWithRedirectionToTaskSchedulerForProcess();
+      SequencedWorkerPool::ResetRedirectToTaskSchedulerForProcessForTesting();
+      SequencedWorkerPool::RedirectToTaskSchedulerForProcess();
     }
   }
 
@@ -271,12 +267,7 @@
     DeletePool();
 
     if (RedirectedToTaskScheduler()) {
-      // Reset SequencedWorkerPool to its original state (i.e. enabled without
-      // redirection to TaskScheduler).
-      SequencedWorkerPool::DisableForProcessForTesting();
-      SequencedWorkerPool::EnableForProcess();
-
-      // Delete the registered TaskScheduler.
+      SequencedWorkerPool::ResetRedirectToTaskSchedulerForProcessForTesting();
       DeleteTaskScheduler();
     }
   }