Linux: remove unmaintained SELinux code.

build/common.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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 903 matching lines @@
     # flag allows us to have warnings as errors in general to prevent
     # regressions in most modules, while working on the bits that are
     # remaining.
     'win_third_party_warn_as_error%': 'true',
 
     # This is the location of the sandbox binary. Chrome looks for this before
     # running the zygote process. If found, and SUID, it will be used to
     # sandbox the zygote process and, thus, all renderer processes.
     'linux_sandbox_path%': '',
 
-    # Set this to true to enable SELinux support.
-    'selinux%': 0,
-
     # Clang stuff.
     'clang%': '<(clang)',
     'make_clang_dir%': 'third_party/llvm-build/Release+Asserts',
 
     # These two variables can be set in GYP_DEFINES while running
     # |gclient runhooks| to let clang run a plugin in every compilation.
     # Only has an effect if 'clang=1' is in GYP_DEFINES as well.
     # Example:
     #     GYP_DEFINES='clang=1 clang_load=/abs/path/to/libPrintFunctionNames.dylib clang_add_plugin=print-fns' gclient runhooks
 
@@ skipping 1060 matching lines @@
                   'release_extra_cflags': '-g1',
                 },
               }],
             ],
           }], # clang!=1
         ],
       }],  # fastbuild!=0
       ['dcheck_always_on!=0', {
         'defines': ['DCHECK_ALWAYS_ON=1'],
       }],  # dcheck_always_on!=0
-      ['selinux==1', {
-        'defines': ['CHROMIUM_SELINUX=1'],
-      }],
       ['win_use_allocator_shim==0', {
         'conditions': [
           ['OS=="win"', {
             'defines': ['NO_TCMALLOC'],
           }],
         ],
       }],
       ['enable_gpu==1', {
         'defines': [
           'ENABLE_GPU=1',
@@ skipping 2425 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }