Store Origin Trials public key in browser prefs

chrome/browser/prefs/origin_trial_prefs.cc

+// Copyright (c) 2016 The Chromium Authors. All rights reserved.

[Will Harris, 2016/06/08 21:35:27]

nit: no (c)

[iclelland, 2016/06/09 03:06:39]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/prefs/origin_trial_prefs.h"
+
+#include "chrome/common/pref_names.h"
+#include "components/prefs/pref_registry_simple.h"
+
+// static
+void OriginTrialPrefs::RegisterPrefs(PrefRegistrySimple* registry) {
+  registry->RegisterStringPref(prefs::kOriginTrialPublicKey, "");

[Will Harris, 2016/06/08 21:35:27]

Is it okay for the default key to be "" - this will be the key used for first
run and until the component updater has run for the first time (normally a few
minutes into startup).

Do you consider hard coding a default key, or maybe that is done somewhere else?

[iclelland, 2016/06/09 03:06:39]

It won't hurt -- there is a default hard-coded key (see
chrome/common/origin_trials/origin_trial_key_manager.cc), and attempting to set
the key to an empty string will just fail.

It's not great, though; I'd rather not deliberately call it with an invalid
value. I've changed it to test whether the value is an empty string, and if so,
not to set any command-line flag for it.

(Incidentally, the first patch in this CL had a default key here, but we
realized that it was unnecessarily duplicating the value)

+}