Remove ThreadRestrictions::ScopedAllowSingleton.

ios/web/web_thread_impl.cc

 // Copyright 2014 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 "ios/web/web_thread_impl.h"
 
 #include <string>
 
 #include "base/atomicops.h"
 #include "base/bind.h"
@@ skipping 350 matching lines @@
     return false;
 
   WebThreadGlobals& globals = g_globals.Get();
   base::AutoLock lock(globals.lock);
   DCHECK(identifier >= 0 && identifier < ID_COUNT);
   return globals.threads[identifier] != nullptr;
 }
 
 // static
 bool WebThread::CurrentlyOn(ID identifier) {
-  // This shouldn't use MessageLoop::current() since it uses LazyInstance which
-  // may be deleted by ~AtExitManager when a WorkerPool thread calls this
-  // function.
-  // http://crbug.com/63678
-  base::ThreadRestrictions::ScopedAllowSingleton allow_singleton;
   WebThreadGlobals& globals = g_globals.Get();
   base::AutoLock lock(globals.lock);
   DCHECK(identifier >= 0 && identifier < ID_COUNT);
   return globals.threads[identifier] &&
          globals.threads[identifier]->message_loop() ==
              base::MessageLoop::current();
 }
 
 // static
 std::string WebThread::GetDCheckCurrentlyOnErrorMessage(ID expected) {
@@ skipping 63 matching lines @@
                                  const base::Closure& reply) {
   return GetTaskRunnerForThread(identifier)
       ->PostTaskAndReply(from_here, task, reply);
 }
 
 // static
 bool WebThread::GetCurrentThreadIdentifier(ID* identifier) {
   if (g_globals == nullptr)
     return false;
 
-  // This shouldn't use MessageLoop::current() since it uses LazyInstance which
-  // may be deleted by ~AtExitManager when a WorkerPool thread calls this
-  // function.
-  // http://crbug.com/63678
-  base::ThreadRestrictions::ScopedAllowSingleton allow_singleton;
   base::MessageLoop* cur_message_loop = base::MessageLoop::current();
   WebThreadGlobals& globals = g_globals.Get();
   for (int i = 0; i < ID_COUNT; ++i) {
     if (globals.threads[i] &&
         globals.threads[i]->message_loop() == cur_message_loop) {
       *identifier = globals.threads[i]->identifier_;
       return true;
     }
   }
 
@@ skipping 13 matching lines @@
   AtomicWord* storage =
       reinterpret_cast<AtomicWord*>(&globals.thread_delegates[identifier]);
   AtomicWord old_pointer = base::subtle::NoBarrier_AtomicExchange(
       storage, reinterpret_cast<AtomicWord>(delegate));
 
   // This catches registration when previously registered.
   DCHECK(!delegate || !old_pointer);
 }
 
 }  // namespace web