Lower the I/O priority of the installer when resonable.

chrome/chrome_installer.gypi

 # 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.
 
 {
   'variables': {
     'lastchange_path': '../build/util/LASTCHANGE',
     'libpeer_target_type%': 'static_library',
     # 'branding_dir' is set in the 'conditions' section at the bottom.
   },
@@ skipping 415 matching lines @@
             'installer/setup/install_worker.cc',        # Move to lib
             'installer/setup/install_worker.h',         # Move to lib
             'installer/setup/install_worker_unittest.cc',
             'installer/setup/run_all_unittests.cc',
             'installer/setup/setup_constants.cc',       # Move to lib
             'installer/setup/setup_constants.h',        # Move to lib
             'installer/setup/setup_unittests.rc',
             'installer/setup/setup_unittests_resource.h',
             'installer/setup/setup_util.cc',
             'installer/setup/setup_util_unittest.cc',
+            'installer/setup/setup_util_unittest.h',
           ],
           'rules': [
             {
               'rule_name': 'server_dlls',               # Move to lib
               'extension': 'release',
               'variables': {
                 'scan_server_dlls_py' : 'tools/build/win/scan_server_dlls.py',
                 'template_file': 'installer/mini_installer/chrome.release',
               },
               'inputs': [
@@ skipping 764 matching lines @@
          'branding_dir_100': 'app/theme/default_100_percent/google_chrome',
       },
     }, { # else branding!="Chrome"
       'variables': {
          'branding_dir': 'app/theme/chromium',
          'branding_dir_100': 'app/theme/default_100_percent/chromium',
       },
     }],
   ],
 }