Define canonical enum for "HeliumResult" status values.

blimp/net/helium/helium_errors.h

Index: blimp/net/helium/helium_errors.h
diff --git a/blimp/net/helium/helium_errors.h b/blimp/net/helium/helium_errors.h
new file mode 100644
index 0000000000000000000000000000000000000000..c2c97e175b49493ae948408115daf7888b7b8b02
--- /dev/null
+++ b/blimp/net/helium/helium_errors.h
@@ -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.
+
+// This file intentionally does not have header guards, it's included
+// inside a macro to generate enum values.
+
+// This file contains the list of Helium error codes.
+
+// A generic failure occurred.
+HELIUM_ERROR(FAILED, 1)

[Garrett Casto, 2016/10/03 18:40:47]

Nit: OK, FAILED, and CONNECTION_LOST were spelled SUCCESS, INTERNAL_ERROR, and
DISCONNECTED in the doc. I don't want to hold this up nit-picking the names (I
haven't thought about them enough to know for certain which I think are better)
but we might want to spend 15 minutes talking this out at some point. Getting
good names is useful as they can be quite sticky.

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

OK, I'll add those. This CL is primarily about establishing a container for
where to put the codes, and logic for stringifying the codes.

Discussion about what might go in our error space could be a good teamwide
topic.

+
+// The operation could not be performed because the connection to the peer was
+// lost.
+HELIUM_ERROR(CONNECTION_LOST, 2)

[scf, 2016/10/03 17:57:44]

move the comment into a string? and use this for the |ToString|?

i.e.
HELIUM_ERROR(FAILED, 1, "Generic failure occured")

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

That could be nice for logging, but I am a little wary that it could be used a
crutch for half-assing enum value naming. And these are inherently not
localizable, so we can't put them on the UI.