Disallow posting tasks to SequencedWorkerPools by default.

chrome/service/service_process.cc

Index: chrome/service/service_process.cc
diff --git a/chrome/service/service_process.cc b/chrome/service/service_process.cc
index a29cc1db80d361012977c1c1e26707d148b9cd15..241af3f9066275ae62ce74d2098fe9464ee7eddc 100644
--- a/chrome/service/service_process.cc
+++ b/chrome/service/service_process.cc
@@ -157,6 +157,12 @@ bool ServiceProcess::Initialize(base::MessageLoopForUI* message_loop,
     Teardown();
     return false;
   }
+
+  // Enable SequencedWorkerPool in the service process.
+  // TODO(fdoray): Remove this once the SequencedWorkerPool to TaskScheduler
+  // redirection experiment concludes https://crbug.com/622400.
+  base::SequencedWorkerPool::EnableForProcess();
+
   blocking_pool_ = new base::SequencedWorkerPool(
       3, "ServiceBlocking", base::TaskPriority::USER_VISIBLE);