Add TaskPriority as a parameter to SequencedWorkerPool in preparation for TaskScheduler experiment.

services/shell/standalone/context.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "services/shell/standalone/context.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 120 matching lines @@
         command_line.GetSwitchValueASCII(::switches::kTraceStartup),
         command_line.GetSwitchValueASCII(::switches::kTraceStartupDuration),
         "mojo_runner.trace");
   }
 
   if (!init_params || init_params->init_edk)
     EnsureEmbedderIsInitialized();
 
   service_manager_runner_ = base::ThreadTaskRunnerHandle::Get();
   blocking_pool_ =
-      new base::SequencedWorkerPool(kMaxBlockingPoolThreads, "blocking_pool");
+      new base::SequencedWorkerPool(kMaxBlockingPoolThreads, "blocking_pool",
+                                    base::TaskPriority::USER_VISIBLE);
 
   init_edk_ = !init_params || init_params->init_edk;
   if (init_edk_) {
     mojo::edk::InitIPCSupport(this, io_thread_->task_runner().get());
 #if defined(OS_MACOSX)
     mojo::edk::SetMachPortProvider(MachBroker::GetInstance()->port_provider());
 #endif
   }
 
   std::unique_ptr<NativeRunnerFactory> runner_factory;
@@ skipping 103 matching lines @@
 
   std::unique_ptr<ConnectParams> params(new ConnectParams);
   params->set_source(CreateServiceManagerIdentity());
   params->set_target(Identity(name, mojom::kRootUserID));
   params->set_remote_interfaces(mojo::GetProxy(&remote_interfaces));
   params->set_local_interfaces(std::move(local_interfaces));
   service_manager_->Connect(std::move(params));
 }
 
 }  // namespace shell