Revert of Do not block in SimpleThread::Start().

base/threading/sequenced_worker_pool.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 "base/threading/sequenced_worker_pool.h"
 
 #include <stdint.h>
 
 #include <list>
 #include <map>
@@ skipping 959 matching lines @@
     return shutdown_called_;
 }
 
 void SequencedWorkerPool::Inner::ThreadLoop(Worker* this_worker) {
   DCHECK_EQ(AllPoolsState::USE_WORKER_POOL, g_all_pools_state);
   {
     AutoLock lock(lock_);
     DCHECK(thread_being_created_);
     thread_being_created_ = false;
     auto result = threads_.insert(
-        std::make_pair(PlatformThread::CurrentId(), WrapUnique(this_worker)));
+        std::make_pair(this_worker->tid(), WrapUnique(this_worker)));
     DCHECK(result.second);
 
     while (true) {
 #if defined(OS_MACOSX)
       base::mac::ScopedNSAutoreleasePool autorelease_pool;
 #endif
 
       HandleCleanup();
 
       // See GetWork for what delete_these_outside_lock is doing.
@@ skipping 635 matching lines @@
 bool SequencedWorkerPool::IsShutdownInProgress() {
   return inner_->IsShutdownInProgress();
 }
 
 bool SequencedWorkerPool::IsRunningSequenceOnCurrentThread(
     SequenceToken sequence_token) const {
   return inner_->IsRunningSequenceOnCurrentThread(sequence_token);
 }
 
 }  // namespace base