Define canonical enum for "HeliumResult" status values.

blimp/net/helium/helium_result.cc

+// 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 "blimp/net/helium/helium_result.h"
+
+namespace blimp {
+
+const char* HeliumResultToString(HeliumResult result) {
+  switch (result) {
+    case HeliumResult::OK:
+      return "OK";
+      break;
+#define HELIUM_ERROR(label, value) \
+    case HeliumResult::ERR_##label: \
+      return "ERR_" #label;
+      break;
+#include "blimp/net/helium/helium_errors.h"

[CJ, 2016/10/03 20:47:33]

Just for my own knowledge, why does the include come last in this case?

[Kevin M, 2016/10/03 22:32:19]

This is an unconventional use of preprocessor includes which basically generates
a bunch of inline code using the HELIUM_ERROR defines. It's not actually *last*
here; it's surrounded by a switch block.

[CJ, 2016/10/03 22:36:31]

I get that a switch statement is being created, I was just curious if the
include has to be within the macro. (still learning macros, so sorry if your
answer already covered this, and I missed it).

+#undef HELIUM_ERROR
+  }
+}
+
+}  // namespace blimp
+