[Remote suggestions] Refactor the scheduler

components/ntp_snippets/remote/remote_suggestions_scheduler_impl.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_
+#ifndef COMPONENTS_NTP_SNIPPETS_REMOTE_REMOTE_SUGGESTIONS_SCHEDULER_IMPL_H_
+#define COMPONENTS_NTP_SNIPPETS_REMOTE_REMOTE_SUGGESTIONS_SCHEDULER_IMPL_H_
 
 #include <memory>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/macros.h"
+#include "base/time/clock.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"
 #include "components/web_resource/eula_accepted_notifier.h"
 
 class PrefRegistrySimple;
 class PrefService;
 
 namespace base {
 class Clock;
 }
 
 namespace ntp_snippets {
 
 struct Status;
 class EulaState;
 class UserClassifier;
 
-// A wrapper around RemoteSuggestionsProvider that introduces periodic fetching.
-//
-// The class initiates fetches on its own in these situations:
-//  - initial fetch when the provider is constructed and we have no suggestions;
-//  - regular fetches according to its schedule.
-// TODO(jkrcal): After soft fetch on Chrome startup is introduced, remove
-// the initial fetch completely.
-//
-// The class also needs to understand when last fetch trials and successful
-// fetches happen and thus it intercepts following interactive fetch requests:
-//  - Fetch() - after "More" button of a remote section is pressed in the UI;
-// TODO(jkrcal): Clarify what Fetch() should do for this provider and maybe stop
-// intercepting it.
-// TODO(jkrcal): Intercept also ReloadSuggestions() call (after the user swipes
-// away everything incl. all empty sections and presses "More"); Not done in the
-// first shot because  it implements a public interface function without any
-// callback.
-// This class is final because it does things in its constructor which make it
-// unsafe to derive from it.
-// TODO(jkrcal): Introduce two-phase initialization and make the class not
-// final? (see the same comment for RemoteSuggestionsProvider)
-// TODO(jkrcal): Change the interface to ContentSuggestionsProvider. We do not
-// need any special functionality, all special should be exposed in the
-// Scheduler interface. crbug.com/695447
-class SchedulingRemoteSuggestionsProvider final
-    : public RemoteSuggestionsProvider,
-      public RemoteSuggestionsScheduler {
+// A client of RemoteSuggestionsProvider that introduces periodic fetching.
+class RemoteSuggestionsSchedulerImpl : public RemoteSuggestionsScheduler {
  public:
-  SchedulingRemoteSuggestionsProvider(
-      Observer* observer,
-      std::unique_ptr<RemoteSuggestionsProvider> provider,
-      PersistentScheduler* persistent_scheduler,
-      const UserClassifier* user_classifier,
-      PrefService* profile_prefs,
-      PrefService* local_state_prefs,
-      std::unique_ptr<base::Clock> clock);
+  RemoteSuggestionsSchedulerImpl(PersistentScheduler* persistent_scheduler,
+                                 const UserClassifier* user_classifier,
+                                 PrefService* profile_prefs,
+                                 PrefService* local_state_prefs,
+                                 std::unique_ptr<base::Clock> clock);
 
-  ~SchedulingRemoteSuggestionsProvider() override;
+  ~RemoteSuggestionsSchedulerImpl();
 
   static void RegisterProfilePrefs(PrefRegistrySimple* registry);
 
   // RemoteSuggestionsScheduler implementation.
+  void SetProvider(RemoteSuggestionsProvider* provider) override;
   void OnProviderActivated() override;
   void OnProviderDeactivated() override;
   void OnSuggestionsCleared() override;
   void OnHistoryCleared() override;
   void RescheduleFetching() override;
+  bool AcquireQuotaForInteractiveFetch() override;
+  void OnInteractiveFetchFinished(Status fetch_status) override;
   void OnPersistentSchedulerWakeUp() override;
   void OnBrowserForegrounded() override;
   void OnBrowserColdStart() override;
   void OnNTPOpened() override;
 
-  // RemoteSuggestionsProvider implementation.
-  void RefetchInTheBackground(
-      std::unique_ptr<FetchStatusCallback> callback) override;
-  const RemoteSuggestionsFetcher* suggestions_fetcher_for_debugging()
-      const override;
-
-  // ContentSuggestionsProvider implementation.
-  CategoryStatus GetCategoryStatus(Category category) override;
-  CategoryInfo GetCategoryInfo(Category category) override;
-  void DismissSuggestion(const ContentSuggestion::ID& suggestion_id) override;
-  void FetchSuggestionImage(const ContentSuggestion::ID& suggestion_id,
-                            const ImageFetchedCallback& callback) override;
-  void Fetch(const Category& category,
-             const std::set<std::string>& known_suggestion_ids,
-             const FetchDoneCallback& callback) override;
-  void ReloadSuggestions() override;
-  void ClearHistory(
-      base::Time begin,
-      base::Time end,
-      const base::Callback<bool(const GURL& url)>& filter) override;
-  void ClearCachedSuggestions(Category category) override;
-  void OnSignInStateChanged() override;
-  void GetDismissedSuggestionsForDebugging(
-      Category category,
-      const DismissedSuggestionsCallback& callback) override;
-  void ClearDismissedSuggestionsForDebugging(Category category) override;
-
  private:
   // Abstract description of the fetching schedule.
   struct FetchingSchedule {
     static FetchingSchedule Empty();
     bool operator==(const FetchingSchedule& other) const;
     bool operator!=(const FetchingSchedule& other) const;
     bool is_empty() const;
 
     base::TimeDelta interval_persistent_wifi;
     base::TimeDelta interval_persistent_fallback;
     base::TimeDelta interval_soft_on_usage_event;
     base::TimeDelta interval_soft_on_ntp_opened;
   };
 
   enum class TriggerType;
 
   // After the call, updates will be scheduled in the future. Idempotent, can be
   // run any time later without impacting the current schedule.
   // If you want to enforce rescheduling, call Unschedule() and then Schedule().
   void StartScheduling();
 
   // After the call, no updates will happen before another call to Schedule().
   // Idempotent, can be run any time later without impacting the current
   // schedule.
   void StopScheduling();
 
   // Trigger a background refetch for the given |trigger| if enabled.
   void RefetchInTheBackgroundIfEnabled(TriggerType trigger);
 
+  // Trigger the background refetch.
+  void RefetchInTheBackground();
+
   // 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 AcquireQuota(bool interactive_request);
 
-  // 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,
-      Status fetch_status);
+  void RefetchInTheBackgroundFinished(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;
 
   // Load and store |schedule_|.
   void LoadLastFetchingSchedule();
   void StoreFetchingSchedule();
 
   // Applies the persistent schedule given by |schedule_|.
   void ApplyPersistentFetchingSchedule();
 
   // Gets enabled trigger types from the variation parameter.
   std::set<TriggerType> GetEnabledTriggerTypes();
 
   // Gets trigger types enabled by default.
   std::set<TriggerType> GetDefaultEnabledTriggerTypes();
 
-  // Interface for doing all the actual work (apart from scheduling).
-  std::unique_ptr<RemoteSuggestionsProvider> provider_;
-
   // Interface for scheduling hard fetches, OS dependent. Not owned, may be
   // null.
   PersistentScheduler* persistent_scheduler_;
 
+  // Interface for doing all the actual work (apart from scheduling). Not owned.
+  RemoteSuggestionsProvider* provider_;
+
   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_;
 
   // We should not fetch in background before EULA gets accepted.
   std::unique_ptr<EulaState> eula_state_;
 
   PrefService* profile_prefs_;
   std::unique_ptr<base::Clock> clock_;
-  std::set<SchedulingRemoteSuggestionsProvider::TriggerType> enabled_triggers_;
+  std::set<TriggerType> enabled_triggers_;
 
   base::Time background_fetches_allowed_after_;
 
-  DISALLOW_COPY_AND_ASSIGN(SchedulingRemoteSuggestionsProvider);
+  DISALLOW_COPY_AND_ASSIGN(RemoteSuggestionsSchedulerImpl);
 };
 
 }  // namespace ntp_snippets
 
-#endif  // COMPONENTS_NTP_SNIPPETS_REMOTE_SCHEDULING_REMOTE_SUGGESTIONS_PROVIDER_H_
+#endif  // COMPONENTS_NTP_SNIPPETS_REMOTE_REMOTE_SUGGESTIONS_SCHEDULER_IMPL_H_