Disable circular gyp dependency check on Mac

build/gyp_chromium

Index: build/gyp_chromium
diff --git a/build/gyp_chromium b/build/gyp_chromium
index 4ed15bac29c625703530aced70f5ebb1dd64dc32..f6b498c703b6895ad06b502fc4c2f1823b39b706 100755
--- a/build/gyp_chromium
+++ b/build/gyp_chromium
@@ -254,6 +254,8 @@ if __name__ == '__main__':
     else:
       args.append(os.path.join(script_dir, 'all.gyp'))
 
+  supplemental_includes = GetSupplementalFiles()
+  gyp_vars_dict = GetGypVars(supplemental_includes)
   # There shouldn't be a circular dependency relationship between .gyp files,
   # but in Chromium's .gyp files, on non-Mac platforms, circular relationships
   # currently exist.  The check for circular dependencies is currently
@@ -263,7 +265,7 @@ if __name__ == '__main__':
   # option.  http://crbug.com/35878.
   # TODO(tc): Fix circular dependencies in ChromiumOS then add linux2 to the
   # list.
-  if sys.platform not in ('darwin',):
+  if gyp_vars_dict.get('OS') != 'ios':
     args.append('--no-circular-check')
 
   # We explicitly don't support the make gyp generator (crbug.com/348686). Be
@@ -285,9 +287,6 @@ if __name__ == '__main__':
   if syntax_check and int(syntax_check):
     args.append('--check')
 
-  supplemental_includes = GetSupplementalFiles()
-  gyp_vars_dict = GetGypVars(supplemental_includes)
-
   # TODO(dmikurube): Remove these checks and messages after a while.
   if ('linux_use_tcmalloc' in gyp_vars_dict or
       'android_use_tcmalloc' in gyp_vars_dict):