Change NTPSnippetsService to implement ContentSuggestionsProvider

components/ntp_snippets/ntp_snippets_service.h

 // Copyright 2015 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_NTP_SNIPPETS_SERVICE_H_
 #define COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_SERVICE_H_
 
 #include <stddef.h>
 
 #include <memory>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "base/timer/timer.h"
 #include "components/image_fetcher/image_fetcher_delegate.h"
 #include "components/keyed_service/core/keyed_service.h"
+#include "components/ntp_snippets/content_suggestion.h"
+#include "components/ntp_snippets/content_suggestions_provider.h"
 #include "components/ntp_snippets/ntp_snippet.h"
 #include "components/ntp_snippets/ntp_snippets_fetcher.h"
 #include "components/ntp_snippets/ntp_snippets_scheduler.h"
 #include "components/ntp_snippets/ntp_snippets_status_service.h"
 #include "components/suggestions/suggestions_service.h"
 #include "components/sync_driver/sync_service_observer.h"
 
 class PrefRegistrySimple;
 class PrefService;
 class SigninManagerBase;
@@ skipping 20 matching lines @@
 class SyncService;
 }
 
 namespace ntp_snippets {
 
 class NTPSnippetsDatabase;
 class NTPSnippetsServiceObserver;
 
 // Stores and vends fresh content data for the NTP.
 class NTPSnippetsService : public KeyedService,
-                           public image_fetcher::ImageFetcherDelegate {
+                           public image_fetcher::ImageFetcherDelegate,
+                           public ContentSuggestionsProvider {
  public:
   using ImageFetchedCallback =
-      base::Callback<void(const std::string& snippet_id, const gfx::Image&)>;
+      base::Callback<void(const std::string& suggestion_id, const gfx::Image&)>;
 
   // |application_language_code| should be a ISO 639-1 compliant string, e.g.
   // 'en' or 'en-US'. Note that this code should only specify the language, not
   // the locale, so 'en_US' (English language with US locale) and 'en-GB_US'
   // (British English person in the US) are not language codes.
   NTPSnippetsService(bool enabled,
                      PrefService* pref_service,
                      suggestions::SuggestionsService* suggestions_service,
                      const std::string& application_language_code,
                      NTPSnippetsScheduler* scheduler,
@@ skipping 43 matching lines @@
   // Returns a reason why the service is disabled, or DisabledReason::NONE
   // if it's not.
   DisabledReason disabled_reason() const {
     return snippets_status_service_->disabled_reason();
   }
 
   // (Re)schedules the periodic fetching of snippets. This is necessary because
   // the schedule depends on the time of day.
   void RescheduleFetching();
 
-  // Fetches the image for the snippet with the given |snippet_id| and runs the
-  // |callback|. If that snippet doesn't exist or the fetch fails, the callback
-  // gets a null image.
-  void FetchSnippetImage(const std::string& snippet_id,
-                         const ImageFetchedCallback& callback);
-
-  // Deletes all currently stored snippets.
-  void ClearSnippets();
-
-  // Discards the snippet with the given |snippet_id|, if it exists. Returns
-  // true iff a snippet was discarded.
-  bool DiscardSnippet(const std::string& snippet_id);
-
-  // Clears the lists of snippets previously discarded by the user.
-  void ClearDiscardedSnippets();
+  // ContentSuggestionsProvider implementation
+  // TODO(pke): At some point reorder the implementations in the .cc file
+  // accordingly.
+  void SetObserver(Observer* observer) override;
+  ContentSuggestionsCategoryStatus GetCategoryStatus(
+      ContentSuggestionsCategory category) override;
+  void DiscardSuggestion(const std::string& suggestion_id) override;
+  void FetchSuggestionImage(const std::string& suggestion_id,
+                            const ImageFetchedCallback& callback) override;
+  void ClearCachedSuggestionsForDebugging() override;
+  void ClearDiscardedSuggestionsForDebugging() override;
 
   // Returns the lists of suggestion hosts the snippets are restricted to.
   std::set<std::string> GetSuggestionsHosts() const;
 
   // Observer accessors.
   void AddObserver(NTPSnippetsServiceObserver* observer);
   void RemoveObserver(NTPSnippetsServiceObserver* observer);
 
   // Returns the maximum number of snippets that will be shown at once.
   static int GetMaxSnippetCountForTesting();
 
  private:
   FRIEND_TEST_ALL_PREFIXES(NTPSnippetsServiceTest, HistorySyncStateChanges);
 
+  // TODO(pke): As soon as the DisabledReason is replaced with the new status,
+  // also remove the old State enum and replace it with
+  // ContentSuggestionsCategoryStatus and a similar status diagram.
   // Possible state transitions:
   //  +------- NOT_INITED ------+
   //  |        /       \        |
   //  |   READY <--> DISABLED <-+
   //  |       \        /
   //  +-----> SHUT_DOWN
   enum class State {
     // The service has just been created. Can change to states:
     // - DISABLED: if the constructor was called with |enabled == false| . In
     //             that case the service will stay disabled until it is shut
@@ skipping 63 matching lines @@
 
   void FetchSnippetImageFromNetwork(const std::string& snippet_id,
                                     const ImageFetchedCallback& callback);
 
   // Triggers a state transition depending on the provided reason to be
   // disabled (or lack thereof). This method is called when a change is detected
   // by |snippets_status_service_|
   void UpdateStateForStatus(DisabledReason disabled_reason);
 
   // Verifies state transitions (see |State|'s documentation) and applies them.
-  // Does nothing if called with the current state.
-  void EnterState(State state);
+  // Also updates the provider status. Does nothing except updating the provider
+  // status if called with the current state.
+  void EnterState(State state, ContentSuggestionsCategoryStatus status);
 
   // Enables the service and triggers a fetch if required. Do not call directly,
   // use |EnterState| instead.
   void EnterStateEnabled(bool fetch_snippets);
 
   // Disables the service. Do not call directly, use |EnterState| instead.
   void EnterStateDisabled();
 
   // Applies the effects of the transition to the SHUT_DOWN state. Do not call
   // directly, use |EnterState| instead.
   void EnterStateShutdown();
 
   void ClearDeprecatedPrefs();
 
+  // Converts the cached snippets to article content suggestions and notifies
+  // the observers.
+  void NotifyNewSuggestions();
+
+  // Notifies the content suggestions observer about a change in the
+  // |category_status_|.
+  void NotifyCategoryStatusChanged();
+
   State state_;
 
+  ContentSuggestionsCategoryStatus category_status_;
+
   PrefService* pref_service_;
 
   suggestions::SuggestionsService* suggestions_service_;
 
   // All current suggestions (i.e. not discarded ones).
   NTPSnippet::PtrVector snippets_;
 
   // Suggestions that the user discarded. We keep these around until they expire
   // so we won't re-add them on the next fetch.
   NTPSnippet::PtrVector discarded_snippets_;
 
   // The ISO 639-1 code of the language used by the application.
   const std::string application_language_code_;
 
   // The observers.
+  // TODO(pke): This is an old kind of observers that will be removed.
   base::ObserverList<NTPSnippetsServiceObserver> observers_;
 
+  // The observer to deliver data to.
+  Observer* observer_;
+
   // Scheduler for fetching snippets. Not owned.
   NTPSnippetsScheduler* scheduler_;
 
   // The subscription to the SuggestionsService. When the suggestions change,
   // SuggestionsService will call |OnSuggestionsChanged|, which triggers an
   // update to the set of snippets.
   using SuggestionsSubscription =
       suggestions::SuggestionsService::ResponseCallbackList::Subscription;
   std::unique_ptr<SuggestionsSubscription> suggestions_service_subscription_;
 
@@ skipping 12 matching lines @@
   // The service that provides events and data about the signin and sync state.
   std::unique_ptr<NTPSnippetsStatusService> snippets_status_service_;
 
   // Set to true if FetchSnippets is called before the database has been loaded.
   // The fetch will be executed after the database load finishes.
   bool fetch_after_load_;
 
   DISALLOW_COPY_AND_ASSIGN(NTPSnippetsService);
 };
 
+// TODO(pke): Remove this when snippets internals don't access this service
+// directly anymore.
 class NTPSnippetsServiceObserver {
  public:
   // Sent every time the service loads a new set of data.
   virtual void NTPSnippetsServiceLoaded() = 0;
 
   // Sent when the service is shutting down.
   virtual void NTPSnippetsServiceShutdown() = 0;
 
   // Sent when the state of the service is changing. Something changed in its
   // dependencies so it's notifying observers about incoming data changes.
   // If the service might be enabled, DisabledReason::NONE will be provided.
   virtual void NTPSnippetsServiceDisabledReasonChanged(DisabledReason) = 0;
 
  protected:
   virtual ~NTPSnippetsServiceObserver() {}
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_SERVICE_H_