[Background fetching] Background fetching when opening an NTP.

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"
 
 class PrefRegistrySimple;
 class PrefService;
 
+namespace base {
+class Clock;
+}
+
 namespace ntp_snippets {
 
 struct Status;
 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.
@@ skipping 15 matching lines @@
 // final? (see the same comment for RemoteSuggestionsProvider)
 class SchedulingRemoteSuggestionsProvider final
     : public RemoteSuggestionsProvider,
       public RemoteSuggestionsScheduler {
  public:
   SchedulingRemoteSuggestionsProvider(
       Observer* observer,
       std::unique_ptr<RemoteSuggestionsProvider> provider,
       PersistentScheduler* persistent_scheduler,
       const UserClassifier* user_classifier,
-      PrefService* pref_service);
+      PrefService* pref_service,
+      std::unique_ptr<base::Clock> clock);
 
   ~SchedulingRemoteSuggestionsProvider() override;
 
   static void RegisterProfilePrefs(PrefRegistrySimple* registry);
 
   // RemoteSuggestionsScheduler implementation.
   void RescheduleFetching() override;
   void OnPersistentSchedulerWakeUp() override;
   void OnBrowserStartup() override;
   void OnNTPOpened() override;
@@ skipping 22 matching lines @@
       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;
+  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;
+  };
 
   // Callback that is notified whenever the status of |provider_| changes.
   void OnProviderStatusChanged(
       RemoteSuggestionsProvider::ProviderStatus status);
 
   // 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();
 
+  // Checks whether it is time to perform a soft background fetch, according to
+  // |schedule|.
+  bool ShouldRefetchInTheBackgroundNow();
+
   // Callback after Fetch is completed.
   void FetchFinished(const FetchDoneCallback& callback,
-                     Status status_code,
+                     Status fetch_status,
                      std::vector<ContentSuggestion> suggestions);
 
+  // Callback after RefetchInTheBackground is completed.
+  void RefetchInTheBackgroundFinished(
+      std::unique_ptr<FetchStatusCallback> callback,
+      Status fetch_status);
+
+  // Common function to call after a fetch of any type is finished.
+  void OnFetchCompleted(Status fetch_status);
+
   FetchingSchedule GetDesiredFetchingSchedule() const;
-  FetchingSchedule GetLastFetchingSchedule() const;
-  void StoreLastFetchingSchedule(const FetchingSchedule& schedule);
 
-  // Common function to call after each fetch.
-  void OnFetchCompleted(Status status);
+  // Load and store |schedule_|.
+  void LoadLastFetchingSchedule();
+  void StoreFetchingSchedule();
+  bool BackgroundFetchesDisabled() const;
 
-  // Applies the provided |schedule|.
-  void ApplyFetchingSchedule(const FetchingSchedule& schedule);
+  // Applies the persistent schedule given by |schedule_|.
+  void ApplyPersistentFetchingSchedule();
 
   // 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_;
 
+  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_;
 
   PrefService* pref_service_;
+  std::unique_ptr<base::Clock> clock_;
 
   DISALLOW_COPY_AND_ASSIGN(SchedulingRemoteSuggestionsProvider);
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_REMOTE_SCHEDULING_REMOTE_SUGGESTIONS_PROVIDER_H_