Revert of Add joinable option to SimpleThread::Options as was just done for Thread.

content/renderer/categorized_worker_pool.cc

 // Copyright 2015 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/categorized_worker_pool.h"
 
 #include <string>
 #include <utility>
 #include <vector>
 
@@ skipping 134 matching lines @@
     threads_.push_back(std::move(thread));
   }
 
   // Start a single thread for background work.
   std::vector<cc::TaskCategory> background_categories;
   background_categories.push_back(cc::TASK_CATEGORY_BACKGROUND);
 
   // Use background priority for background thread.
   base::SimpleThread::Options thread_options;
 #if !defined(OS_MACOSX)
-  thread_options.priority = base::ThreadPriority::BACKGROUND;
+  thread_options.set_priority(base::ThreadPriority::BACKGROUND);
 #endif
 
   std::unique_ptr<base::SimpleThread> thread(new CategorizedWorkerPoolThread(
       "CompositorTileWorkerBackground", thread_options, this,
       background_categories, &has_ready_to_run_background_tasks_cv_));
   thread->Start();
   threads_.push_back(std::move(thread));
 }
 
 void CategorizedWorkerPool::Shutdown() {
@@ skipping 256 matching lines @@
 
 // Overridden from cc::Task:
 void CategorizedWorkerPool::ClosureTask::RunOnWorkerThread() {
   closure_.Run();
   closure_.Reset();
 }
 
 CategorizedWorkerPool::ClosureTask::~ClosureTask() {}
 
 }  // namespace content