headless: Make it possible to configure an HTTP proxy

headless/app/headless_shell_switches.cc

Index: headless/app/headless_shell_switches.cc
diff --git a/headless/app/headless_shell_switches.cc b/headless/app/headless_shell_switches.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c3c6ad7b221d78ce3163a3bc8e15d6b3720a8376
--- /dev/null
+++ b/headless/app/headless_shell_switches.cc
@@ -0,0 +1,15 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "headless/app/headless_shell_switches.h"
+
+namespace headless {
+namespace switches {
+
+// Uses a specified proxy server, overrides system settings. This switch only
+// affects HTTP and HTTPS requests.
+const char kProxyServer[] = "proxy-server";
+
+}  // namespace switches
+}  // namespace headless