Make it possible to disable dbus on linux

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 67f6271a8b92f5999bcd123b95262b66bcd1edaa..0af1214360841c88b6959b640f316b978b9238d1 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -125,6 +125,14 @@
             'toolkit_uses_gtk%': 0,
           }],
 
+          # Whether or not to use D-Bus for core functionality on linux.
+          # (eg use_gconf=1 will still pull in dbus as a dependency).
+          ['OS=="linux"', {
+            'use_dbus%': 1,
+          }, {
+            'use_dbus%': 0,
+          }],
+
           # Enable HiDPI on Mac OS and Chrome OS.
           ['OS=="mac" or chromeos==1', {
             'enable_hidpi%': 1,
@@ -175,6 +183,7 @@
       'enable_message_center%': '<(enable_message_center)',
       'use_default_render_theme%': '<(use_default_render_theme)',
       'buildtype%': '<(buildtype)',
+      'use_dbus%': '<(use_dbus)',
 
       # Override branding to select the desired branding flavor.
       'branding%': 'Chromium',
@@ -763,6 +772,7 @@
     'enable_managed_users%': '<(enable_managed_users)',
     'spdy_proxy_auth_origin%': '<(spdy_proxy_auth_origin)',
     'spdy_proxy_auth_property%': '<(spdy_proxy_auth_property)',
+    'use_dbus%': '<(use_dbus)',
 
     # Use system ffmpeg instead of bundled one.
     'use_system_ffmpeg%': 0,