Allows client to access auth token from command line specified file.

blimp/common/get_client_token.h

Index: blimp/common/get_client_token.h
diff --git a/blimp/common/get_client_token.h b/blimp/common/get_client_token.h
new file mode 100644
index 0000000000000000000000000000000000000000..bc6574d1d76e5e98e1621785e4cde9f979bd14ba
--- /dev/null
+++ b/blimp/common/get_client_token.h
@@ -0,0 +1,22 @@
+// 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.
+
+#ifndef BLIMP_COMMON_GET_CLIENT_TOKEN_H_
+#define BLIMP_COMMON_GET_CLIENT_TOKEN_H_
+
+#include <string>
+
+#include "base/command_line.h"
+#include "blimp/common/blimp_common_export.h"
+
+namespace blimp {
+
+// Gets the client token from the file provided by the command line. If a read
+// does not succeed, or the switch is malformed, an empty string is returned.
+BLIMP_COMMON_EXPORT std::string GetClientToken(
+    const base::CommandLine& cmd_line);
+
+}  // namespace blimp
+
+#endif  // BLIMP_COMMON_GET_CLIENT_TOKEN_H_