In build/gyp_chromium, if CHROMIUM_GYP_SYNTAX_CHECK is set to 1, run gyp with --check.

This is to eventually run gyp with syntax checking enabled on the buildbots.
Enabling that will come in a later CL after all gyp errors are fixed.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/1435001

git-svn-id: http://src.chromium.org/svn/trunk/src/build@42788 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

gyp_chromium

@@ -82,6 +82,12 @@ if __name__ == '__main__':
   if sys.platform != 'darwin':
     args.append('--no-circular-check')
 
+  # If CHROMIUM_GYP_SYNTAX_CHECK is set to 1, it will invoke gyp with --check
+  # to enfore syntax checking.
+  syntax_check = os.environ.get('CHROMIUM_GYP_SYNTAX_CHECK')
+  if syntax_check and int(syntax_check):
+    args.append('--check')
+
   print 'Updating projects from gyp files...'
   sys.stdout.flush()