Temporary whitelist several cases of disk I/O on the UI threads in cros.

base/nss_util.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 "base/nss_util.h"
 #include "base/nss_util_internal.h"
 
 #include <nss.h>
 #include <plarena.h>
 #include <prerror.h>
@@ skipping 147 matching lines @@
 };
 
 LazyInstance<NSPRInitSingleton, LeakyLazyInstanceTraits<NSPRInitSingleton> >
     g_nspr_singleton(LINKER_INITIALIZED);
 
 class NSSInitSingleton {
  public:
 #if defined(OS_CHROMEOS)
   void OpenPersistentNSSDB() {
     if (!chromeos_user_logged_in_) {
+      // GetDefaultConfigDirectory causes us to do blocking IO on UI thread.
+      // Temporarily allow it until we fix http://crbug.com.70119
+      ThreadRestrictions::ScopedAllowIO allow_io;
       chromeos_user_logged_in_ = true;
       real_db_slot_ = OpenUserDB(GetDefaultConfigDirectory(),
                                  "Real NSS database");
     }
   }
 #endif  // defined(OS_CHROMEOS)
 
   bool OpenTestNSSDB(const FilePath& path, const char* description) {
     test_db_slot_ = OpenUserDB(path, description);
     return !!test_db_slot_;
@@ skipping 246 matching lines @@
   exploded.millisecond  = prxtime.tm_usec / 1000;
 
   return Time::FromUTCExploded(exploded);
 }
 
 PK11SlotInfo* GetDefaultNSSKeySlot() {
   return g_nss_singleton.Get().GetDefaultKeySlot();
 }
 
 }  // namespace base