Support getting and deleting token for Instance ID.

google_apis/gcm/base/gcm_util.h

+// Copyright 2015 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 GOOGLE_APIS_GCM_BASE_GCM_UTIL_H_
+#define GOOGLE_APIS_GCM_BASE_GCM_UTIL_H_
+
+#include <string>
+
+namespace gcm {
+
+// Encodes key-value pair into form format that could be submitted as http post
+// data. Each key-value pair is separated by an '&', and each key is separated
+// from its value by an '='.
+void BuildFormEncoding(const std::string& key,
+                       const std::string& value,
+                       std::string* out);
+
+}  // namespace gcm
+
+#endif  // GOOGLE_APIS_GCM_BASE_GCM_UTIL_H_