Add generic functions for getting typed variation parameter values

components/ntp_snippets/remote/remote_suggestions_hard_scheduler.h

+// 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_REMOTE_REMOTE_SUGGESTIONS_HARD_SCHEDULER_H_
+#define COMPONENTS_NTP_SNIPPETS_REMOTE_REMOTE_SUGGESTIONS_HARD_SCHEDULER_H_
+
+#include "base/macros.h"
+#include "base/time/time.h"
+
+namespace ntp_snippets {
+
+// Interface to schedule "hard" periodic fetches of snippets. These "hard"
+// fetches must get triggered according to their schedule independent of whether
+// Chrome is running at that moment.
+class RemoteSuggestionsHardScheduler {
+ public:
+  // Schedule periodic fetching of snippets, with different periods depending on
+  // network state. Once per period, the concrete implementation should call
+  // RemoteSuggestionsScheduler::Updater::HardUpdate() where the updater is
+  // obtained from ContentSuggestionsService. Any of the periods can be zero to
+  // indicate that the corresponding task should not be scheduled.
+  virtual bool Schedule(base::TimeDelta period_wifi,
+                        base::TimeDelta period_fallback) = 0;
+
+  // Cancel any scheduled tasks.
+  virtual bool Unschedule() = 0;
+
+ protected:
+  RemoteSuggestionsHardScheduler() = default;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(RemoteSuggestionsHardScheduler);
+};
+
+}  // namespace ntp_snippets
+
+#endif  // COMPONENTS_NTP_SNIPPETS_REMOTE_REMOTE_SUGGESTIONS_HARD_SCHEDULER_H_