[Remote suggestions] Move the throttler into the Scheduler

components/ntp_snippets/remote/scheduling_remote_suggestions_provider.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_SCHEDULING_REMOTE_SUGGESTIONS_PROVIDER_H_
 #define COMPONENTS_NTP_SNIPPETS_REMOTE_SCHEDULING_REMOTE_SUGGESTIONS_PROVIDER_H_
 
 #include <memory>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "components/ntp_snippets/content_suggestions_provider.h"
 #include "components/ntp_snippets/remote/persistent_scheduler.h"
 #include "components/ntp_snippets/remote/remote_suggestions_provider.h"
 #include "components/ntp_snippets/remote/remote_suggestions_scheduler.h"
+#include "components/ntp_snippets/remote/request_throttler.h"
 
 class PrefRegistrySimple;
 class PrefService;
 
 namespace base {
 class Clock;
 }
 
 namespace ntp_snippets {
 
@@ skipping 109 matching lines @@
   // Trigger a background refetch for the given |trigger| if enabled.
   void RefetchInTheBackgroundIfEnabled(TriggerType trigger);
 
   // Checks whether it is time to perform a soft background fetch, according to
   // |schedule|.
   bool ShouldRefetchInTheBackgroundNow(TriggerType trigger);
 
   // Returns whether background fetching (for the given |trigger|) is disabled.
   bool BackgroundFetchesDisabled(TriggerType trigger) const;
 
+  // Returns true if quota is available for another request.
+  bool DemandQuotaForRequest(bool interactive_request);

[tschumann, 2017/02/24 10:18:08]

nit: would AcquireQuota() be a better name? We have much better context here, so
we can afford shorter names.

[jkrcal, 2017/02/27 10:26:23]

Done.

+
   // Callback after Fetch is completed.
   void FetchFinished(const FetchDoneCallback& callback,
                      Status fetch_status,
                      std::vector<ContentSuggestion> suggestions);
 
   // Callback after RefetchInTheBackground is completed.
   void RefetchInTheBackgroundFinished(
       std::unique_ptr<FetchStatusCallback> callback,

[Marc Treib, 2017/02/24 15:50:35]

Unrelated to this CL, but: Why are we passing around unique_ptrs to callbacks?
Just to make them optional? Callbacks are already "nullable" by themselves, so
let's not add a second layer of nullability.
Or is there some other reason I'm missing?

[jkrcal, 2017/02/27 10:26:23]

This is a known issue. Added a TODO with a bug link to the
remote_suggestions_provider.h interface.

       Status fetch_status);
 
   // Common function to call after a fetch of any type is finished.
   void OnFetchCompleted(Status fetch_status);
 
   // Clears the time of the last fetch so that the provider is ready to make a
   // soft fetch at any later time (upon a trigger).
   void ClearLastFetchAttemptTime();
 
   FetchingSchedule GetDesiredFetchingSchedule() const;
@@ skipping 17 matching lines @@
   // Interface for scheduling hard fetches, OS dependent. Not owned, may be
   // null.
   PersistentScheduler* persistent_scheduler_;
 
   FetchingSchedule schedule_;
   bool background_fetch_in_progress_;
 
   // Used to adapt the schedule based on usage activity of the user. Not owned.
   const UserClassifier* user_classifier_;
 
+  // Request throttlers for limiting requests for different classes of users.
+  RequestThrottler request_throttler_rare_ntp_user_;
+  RequestThrottler request_throttler_active_ntp_user_;
+  RequestThrottler request_throttler_active_suggestions_consumer_;
+
   PrefService* pref_service_;
   std::unique_ptr<base::Clock> clock_;
   std::set<SchedulingRemoteSuggestionsProvider::TriggerType> enabled_triggers_;
 
   base::Time background_fetches_allowed_after_;
 
   DISALLOW_COPY_AND_ASSIGN(SchedulingRemoteSuggestionsProvider);
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_REMOTE_SCHEDULING_REMOTE_SUGGESTIONS_PROVIDER_H_