Make DBUS an optional dependency so Chromium can be built without it....

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.
 
 {
   'conditions': [
     ['sysroot!=""', {
       'variables': {
         'pkg-config': './pkg-config-wrapper "<(sysroot)"',
       },
@@ skipping 305 matching lines @@
                 ],
               },
             }],
           ],
         }],
       ],
     },
     {
       'target_name': 'dbus-glib',
       'type': 'settings',
-      'direct_dependent_settings': {
-        'cflags': [
-          '<!@(<(pkg-config) --cflags dbus-glib-1)',
-        ],
-      },
-      'link_settings': {
-        'ldflags': [
-          '<!@(<(pkg-config) --libs-only-L --libs-only-other dbus-glib-1)',
-        ],
-        'libraries': [
-          '<!@(<(pkg-config) --libs-only-l dbus-glib-1)',
-        ],
-      },
+      'conditions': [
+        ['use_dbus==1 and _toolset=="target"', {
+          'direct_dependent_settings': {
+            'cflags': [
+              '<!@(<(pkg-config) --cflags dbus-glib-1)',
+            ],
+            'defines': [
+              'USE_DBUS',
+            ],
+          },
+          'link_settings': {
+            'ldflags': [
+             '<!@(<(pkg-config) --libs-only-L --libs-only-other dbus-glib-1)',
+            ],
+           'libraries': [
+              '<!@(<(pkg-config) --libs-only-l dbus-glib-1)',
+            ],
+          },
+        }]
+      ]
     },
     {
       'target_name': 'libresolv',
       'type': 'settings',
       'link_settings': {
         'libraries': [
           '-lresolv',
         ],
       },
     },
@@ skipping 22 matching lines @@
       ],
     },
   ],
 }
 
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