Make all the files mapped in when running interactive_ui_tests read only.

chrome/interactive_ui_tests.isolate

 # Copyright 2013 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.
 {
   'conditions': [
     ['OS=="linux"', {
       'variables': {
         'command': [
           '../testing/xvfb.py',
           '<(PRODUCT_DIR)',
@@ skipping 22 matching lines @@
           '<(PRODUCT_DIR)/interactive_ui_tests<(EXECUTABLE_SUFFIX)',
           '<(PRODUCT_DIR)/resources.pak',
         ],
         'isolate_dependency_untracked': [
           '../third_party/pyftpdlib/',
           '../third_party/pywebsocket/src/mod_pywebsocket/',
           '../third_party/tlslite/tlslite/',
           '../tools/swarming_client/',
           'test/data/',
         ],
+        'read_only': 1,
       },
     }],
     ['OS=="linux" or OS=="win"', {
       'variables': {
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/chrome_100_percent.pak',
           '<(PRODUCT_DIR)/locales/en-US.pak',
           '<(PRODUCT_DIR)/locales/fr.pak',
         ],
       },
@@ skipping 33 matching lines @@
         'isolate_dependency_untracked': [
           '<(PRODUCT_DIR)/plugins/npapi_test_plugin.dll',
         ],
       },
     }],
   ],
   'includes': [
     '../third_party/icu/icu.isolate',
   ],
 }