Adding variable builder for mac_gn

masters/master.tryserver.chromium.mac/master.cfg

Index: masters/master.tryserver.chromium.mac/master.cfg
diff --git a/masters/master.tryserver.chromium.mac/master.cfg b/masters/master.tryserver.chromium.mac/master.cfg
index 28ec2163b0e1d60e4429138317618fe3c15c369c..ae180663142360920c68b53563cbf1d5c2bc54cb 100644
--- a/masters/master.tryserver.chromium.mac/master.cfg
+++ b/masters/master.tryserver.chromium.mac/master.cfg
@@ -181,15 +181,20 @@ b_mac_nacl_sdk_build = {
 # and NOT CQ slaves.
 variable_builders = [
   {
+    'name': 'mac_chromium_asan_variable',
+    'factory': m_annotator.BaseFactory('findit/chromium/compile'),
+    'slavebuilddir': 'mac_asan'
+  },
+  {
     'name': 'mac_chromium_variable',
     'factory': m_annotator.BaseFactory('findit/chromium/compile'),
     'slavebuilddir': 'mac'
   },
   {
-    'name': 'mac_chromium_asan_variable',
+    'name': 'mac_chromium_variable_gn',
     'factory': m_annotator.BaseFactory('findit/chromium/compile'),
-    'slavebuilddir': 'mac_asan'
-  }
+    'slavebuilddir': 'mac_gn'
+  },
 ]
 
 c['builders'] = [