Support getting and deleting token for Instance ID.

google_apis/gcm/base/gcm_util.cc

+// 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.
+
+#include "google_apis/gcm/base/gcm_util.h"
+
+#include "net/base/escape.h"
+
+namespace gcm {
+
+void BuildFormEncoding(const std::string& key,
+                       const std::string& value,
+                       std::string* out) {
+  if (!out->empty())
+    out->append("&");
+  out->append(key + "=" + net::EscapeUrlEncodedData(value, true));
+}
+
+}  // namespace gcm