Initialize the simple cache backend at runtime.

PRESUBMIT.py

 # 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.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl.
 """
 
@@ skipping 141 matching lines @@
     ),
     (
       'ScopedAllowIO',
       (
        'New code should not use ScopedAllowIO. Post a task to the blocking',
        'pool or the FILE thread instead.',
       ),
       True,
       (
         r"^content[\\\/]shell[\\\/]shell_browser_main\.cc$",
+        r"^net[\\\/]disk_cache[\\\/]cache_util\.cc$",
       ),
     ),
 )
 
 
 _VALID_OS_MACROS = (
     # Please keep sorted.
     'OS_ANDROID',
     'OS_BSD',
     'OS_CAT',       # For testing.
@@ skipping 767 matching lines @@
       'win_rel',
       'win:compile',
   ]
 
   # Match things like path/aura/file.cc and path/file_aura.cc.
   # Same for chromeos.
   if any(re.search('[/_](aura|chromeos)', f) for f in files):
     trybots += ['linux_chromeos_clang:compile', 'linux_chromeos_asan']
 
   return trybots