[reland] Do not block in SimpleThread::Start().

content/renderer/render_thread_impl.cc

 // Copyright (c) 2012 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 "content/renderer/render_thread_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <utility>
@@ skipping 877 matching lines @@
   GetInterfaceRegistry()->AddInterface(
       base::Bind(&EmbeddedWorkerInstanceClientImpl::Create,
                  base::Unretained(embedded_worker_dispatcher_.get())));
 
   GetConnector()->BindInterface(mojom::kBrowserServiceName,
                                 mojo::MakeRequest(&storage_partition_service_));
 
 #if defined(OS_LINUX)
   ChildProcess::current()->SetIOThreadPriority(base::ThreadPriority::DISPLAY);
   ChildThreadImpl::current()->SetThreadPriority(
-      categorized_worker_pool_->background_worker_thread_id(),
+      categorized_worker_pool_->GetBackgroundWorkerThreadId(),
       base::ThreadPriority::BACKGROUND);
 #endif
 
   record_purge_suspend_metric_closure_.Reset(base::Bind(
       &RenderThreadImpl::RecordPurgeAndSuspendMetrics, base::Unretained(this)));
   record_purge_suspend_growth_metric_closure_.Reset(
       base::Bind(&RenderThreadImpl::RecordPurgeAndSuspendMemoryGrowthMetrics,
                  base::Unretained(this)));
   needs_to_record_first_active_paint_ = false;
 
@@ skipping 1565 matching lines @@
   }
 }
 
 void RenderThreadImpl::OnRendererInterfaceRequest(
     mojom::RendererAssociatedRequest request) {
   DCHECK(!renderer_binding_.is_bound());
   renderer_binding_.Bind(std::move(request));
 }
 
 }  // namespace content