Disallow posting tasks to SequencedWorkerPools by default.

base/test/test_suite.cc

Index: base/test/test_suite.cc
diff --git a/base/test/test_suite.cc b/base/test/test_suite.cc
index a56dc59fecceff86f96180938be3049414e62c32..aaaf8c1b0ac31caa7734f80e423898a1cea412d4 100644
--- a/base/test/test_suite.cc
+++ b/base/test/test_suite.cc
@@ -31,6 +31,7 @@
 #include "base/test/multiprocess_test.h"
 #include "base/test/test_switches.h"
 #include "base/test/test_timeouts.h"
+#include "base/threading/sequenced_worker_pool.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "testing/gmock/include/gmock/gmock.h"
@@ -369,6 +370,11 @@ void TestSuite::Initialize() {
 #endif
 #endif
 
+  // Enable SequencedWorkerPool in tests.
+  // TODO(fdoray): Remove this once the SequencedWorkerPool to TaskScheduler
+  // redirection experiment concludes https://crbug.com/622400.
+  SequencedWorkerPool::EnableForProcess();
+
   CatchMaybeTests();
   ResetCommandLine();
   AddTestLauncherResultPrinter();