Put more files under the enable_service_discovery build flag.

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 993 matching lines @@
           # Currently only supported on Android ARMv7+, ARM64, ia32, x64 and mipsel.
           # When enabled, this will also enable WebAudio support on
           # Android for these architectures.  Default is enabled.  Whether
           # WebAudio is actually available depends on runtime settings
           # and flags.
           'use_openmax_dl_fft%': 1,
         }, {
           'use_openmax_dl_fft%': 0,
         }],
         ['OS=="win" or OS=="linux"', {
-            'enable_mdns%' : 1,
+          'enable_mdns%' : 1,
         }],
 
         # Disable various features by default on embedded.
         ['embedded==1', {
           'remoting%': 0,
           'enable_basic_printing%': 0,
           'enable_print_preview%': 0,
         }],
 
         # Path to sas.dll, which provides the SendSAS function.
@@ skipping 5357 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',
   },
 }