Reland: Fix errors found in Mac gn component builds

sync/sync.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
     # Setting these two variables allows other targets to use the
     # sync_proto_sources variable as the list of sync protocol buffer files.
     'sync_proto_sources_dir': 'protocol',
@@ skipping 443 matching lines @@
         'util/time.h',
       ],
 
       'conditions': [
         ['OS=="linux" and chromeos==1', {
           # Required by get_session_name.cc on Chrome OS.
           'dependencies': [
             '../chromeos/chromeos.gyp:chromeos',
             ],
         }],
+        ['OS=="mac"', {
+          'link_settings': {
+            'libraries': [
+              # Required by get_session_name_mac.mm on Mac.
+              '$(SDKROOT)/System/Library/Frameworks/SystemConfiguration.framework',
+            ]
+          },
+        }],
       ],
     },
     {
       # Contains sync protobuf definitions.  Do not depend on this directly.
       # Depend on the 'sync' target to get the relevant C++ code, too.
       #
       # GN version: //sync/protocol
       'target_name': 'sync_proto',
       'type': '<(component)',
       'include_dirs': [
@@ skipping 40 matching lines @@
       },
       'includes': [
         '../build/protoc.gypi'
       ],
       'defines': [
         'SYNC_IMPLEMENTATION'
       ],
     },
   ],
 }