fix linking on linux by explicitly adding gthread

build/linux/system.gyp

 # Copyright (c) 2009 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.
 
 {
   'targets': [
     {
       'target_name': 'gtk',
       'type': 'settings',
       'direct_dependent_settings': {
@@ skipping 88 matching lines @@
       },
       'link_settings': {
         'ldflags': [
           '<!@(python pkg_config_wrapper.py --libs-only-L --libs-only-other gconf-2.0)',
         ],
         'libraries': [
           '<!@(python pkg_config_wrapper.py --libs-only-l gconf-2.0)',
         ],
       },
     },
+    {
+      'target_name': 'gthread',
+      'type': 'settings',
+      'direct_dependent_settings': {
+        'cflags': [
+          '<!@(python pkg_config_wrapper.py --cflags gthread-2.0)',
+        ],
+      },
+      'link_settings': {
+        'ldflags': [
+          '<!@(python pkg_config_wrapper.py --libs-only-L --libs-only-other gthread-2.0)',
+        ],
+        'libraries': [
+          '<!@(python pkg_config_wrapper.py --libs-only-l gthread-2.0)',
+        ],
+      },
+    },
   ],
 }