base: Introduce SharedMemoryTracker for POSIX (but not macOS)

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 depot_tools.
 """
 
@@ skipping 167 matching lines @@
       ),
     ),
     (
       'ScopedAllowIO',
       (
        'New code should not use ScopedAllowIO. Post a task to the blocking',
        'pool or the FILE thread instead.',
       ),
       True,
       (
+        r"^base[\\\/]memory[\\\/]shared_memory_posix\.cc$",
         r"^base[\\\/]process[\\\/]process_linux\.cc$",
         r"^base[\\\/]process[\\\/]process_metrics_linux\.cc$",
         r"^chrome[\\\/]browser[\\\/]chromeos[\\\/]boot_times_recorder\.cc$",
         r"^chrome[\\\/]browser[\\\/]lifetime[\\\/]application_lifetime\.cc$",
         r"^chrome[\\\/]browser[\\\/]chromeos[\\\/]"
             "customization_document_browsertest\.cc$",
         r"^components[\\\/]crash[\\\/]app[\\\/]breakpad_mac\.mm$",
         r"^content[\\\/]shell[\\\/]browser[\\\/]layout_test[\\\/]" +
             r"test_info_extractor\.cc$",
         r"^content[\\\/].*browser(|_)test[a-zA-Z_]*\.cc$",
@@ skipping 2174 matching lines @@
       output_api,
       json_url='http://chromium-status.appspot.com/current?format=json'))
 
   results.extend(
       input_api.canned_checks.CheckPatchFormatted(input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasBugField(
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasDescription(
       input_api, output_api))
   return results