Mac: turn on file access checks for the IO thread.

chrome/browser/io_thread.cc

 // Copyright (c) 2010 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 "chrome/browser/io_thread.h"
 
 #include "base/command_line.h"
 #include "base/debug/leak_tracker.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
@@ skipping 215 matching lines @@
           this,
           &IOThread::ChangedToOnTheRecordOnIOThread));
 }
 
 net::ProxyScriptFetcher* IOThread::CreateAndRegisterProxyScriptFetcher(
     URLRequestContext* url_request_context) {
   return new ManagedProxyScriptFetcher(url_request_context, this);
 }
 
 void IOThread::Init() {
-#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+#if (defined(OS_LINUX) && !defined(OS_CHROMEOS)) || defined(OS_MACOSX)
   // TODO(evan): test and enable this on all platforms.
   // Though this thread is called the "IO" thread, it actually just routes
   // messages around; it shouldn't be allowed to perform any blocking disk I/O.
   base::ThreadRestrictions::SetIOAllowed(false);
 #endif
 
   BrowserProcessSubThread::Init();
 
   DCHECK_EQ(MessageLoop::TYPE_IO, message_loop()->type());
 
@@ skipping 164 matching lines @@
     net::HostCache* host_cache =
         globals_->host_resolver.get()->GetAsHostResolverImpl()->cache();
     if (host_cache)
       host_cache->clear();
   }
   // Clear all of the passively logged data.
   // TODO(eroman): this is a bit heavy handed, really all we need to do is
   //               clear the data pertaining to off the record context.
   globals_->net_log->passive_collector()->Clear();
 }