[NTP Snippets] Persist the set of snippets in a pref

components/ntp_snippets/pref_names.h

Index: components/ntp_snippets/pref_names.h
diff --git a/components/ntp_snippets/pref_names.h b/components/ntp_snippets/pref_names.h
new file mode 100644
index 0000000000000000000000000000000000000000..d988d48e2d78f27500caf1a9189ee52a07fe381d
--- /dev/null
+++ b/components/ntp_snippets/pref_names.h
@@ -0,0 +1,16 @@
+// 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.
+
+#ifndef COMPONENTS_NTP_SNIPPETS_PREF_NAMES_H_
+#define COMPONENTS_NTP_SNIPPETS_PREF_NAMES_H_
+
+namespace ntp_snippets {
+namespace prefs {
+
+extern const char kSnippets[];
+
+}  // namespace prefs
+}  // namespace ntp_snippets
+
+#endif