GN: support 32-bit x86 builds

infra/bots/recipe_modules/flavor/gn_flavor.py

Index: infra/bots/recipe_modules/flavor/gn_flavor.py
diff --git a/infra/bots/recipe_modules/flavor/gn_flavor.py b/infra/bots/recipe_modules/flavor/gn_flavor.py
index bef577926d4cd02445cc72a8b4102b4725d3d142..fb02a3ae3a2f4520ade8d7a14541b75e180b16d8 100644
--- a/infra/bots/recipe_modules/flavor/gn_flavor.py
+++ b/infra/bots/recipe_modules/flavor/gn_flavor.py
@@ -8,12 +8,15 @@ import default_flavor
 class GNFlavorUtils(default_flavor.DefaultFlavorUtils):
   def supported(self):
     extra_config = self.m.vars.builder_cfg.get('extra_config', '')
+    os           = self.m.vars.builder_cfg.get('os',           '')
+    target_arch  = self.m.vars.builder_cfg.get('target_arch',  '')
 
     return any([
       'SAN' in extra_config,
       extra_config == 'Fast',
       extra_config == 'GN',
-      extra_config.startswith('SK')
+      extra_config.startswith('SK'),
+      os == 'Ubuntu' and target_arch == 'x86',
     ])
 
   def _run(self, title, cmd, env=None, infra_step=False):
@@ -29,6 +32,7 @@ class GNFlavorUtils(default_flavor.DefaultFlavorUtils):
     configuration = self.m.vars.builder_cfg.get('configuration', '')
     extra_config  = self.m.vars.builder_cfg.get('extra_config',  '')
     os            = self.m.vars.builder_cfg.get('os',            '')
+    target_arch   = self.m.vars.builder_cfg.get('target_arch',   '')
 
     clang_linux = str(self.m.vars.slave_dir.join('clang_linux'))
 
@@ -65,6 +69,7 @@ class GNFlavorUtils(default_flavor.DefaultFlavorUtils):
       'extra_cflags':  ' '.join(extra_cflags),
       'extra_ldflags': ' '.join(extra_ldflags),
       'sanitize': extra_config if 'SAN' in extra_config else '',
+      'target_cpu': 'x86' if target_arch == 'x86' else '',
     }.iteritems():
       if v:
         args[k] = '"%s"' % v