Force offline by default for warm benchmarks.

R=ppi@chromium.org

Review URL: https://codereview.chromium.org/1354623002 .

Cr-Mirrored-From: https://github.com/domokit/mojo
Cr-Mirrored-Commit: 9a2585015cc6f342ce543df996f285b9df6559fb
diff --git a/mojo_benchmark b/mojo_benchmark
index 12a80d7..9b24268 100755
--- a/mojo_benchmark
+++ b/mojo_benchmark
@@ -74,6 +74,7 @@
 
   shell_args = list(shell_args)
   shell_args.append(_BENCHMARK_APP)
+  shell_args.append('--force-offline-by-default')
   shell_args.append('--args-for=%s %s' % (_BENCHMARK_APP,
                                           ' '.join(benchmark_args)))