Add ContentSuggestionsService

components/ntp_snippets/content_suggestions_service.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_CONTENT_SUGGESTIONS_SERVICE_H_
+#define COMPONENTS_NTP_SNIPPETS_CONTENT_SUGGESTIONS_SERVICE_H_
+
+#include <stddef.h>
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/callback_forward.h"
+#include "base/observer_list.h"
+#include "components/keyed_service/core/keyed_service.h"
+#include "components/ntp_snippets/content_suggestions_provider.h"
+#include "components/ntp_snippets/content_suggestions_provider_type.h"
+
+namespace gfx {
+class Image;
+}
+
+namespace ntp_snippets {
+
+class ContentSuggestionsServiceObserver;
+
+// Retrieves suggestions from a number of ContentSuggestionsProviders and serves
+// them grouped into categories.
+class ContentSuggestionsService : public KeyedService,
+                                  public ContentSuggestionsProvider::Delegate {
+ public:
+  using ImageFetchedCallback =
+      base::Callback<void(const std::string& suggestion_id, const gfx::Image&)>;
+
+  ContentSuggestionsService(bool enabled);
+  ~ContentSuggestionsService() override;
+
+  // Inherited from KeyedService.
+  void Shutdown() override;
+
+  // Available suggestions
+  const std::map<ContentSuggestionCategory, std::vector<ContentSuggestion>>&
+  suggestions() const {
+    return suggestions_by_category_;
+  }
+  const std::vector<ContentSuggestion>& suggestions(
+      ContentSuggestionCategory category) {
+    return suggestions_by_category_[category];
+  }
+
+  // Fetches the image for the suggestion with the given |suggestion_id| and
+  // runs the |callback|. If that suggestion doesn't exist or the fetch fails,
+  // the callback gets an empty image.
+  void FetchImage(ContentSuggestionsProviderType provider_type,
+                  const std::string& suggestion_id,
+                  const ImageFetchedCallback& callback);
+
+  // Only for debugging use through the internals page.
+  // Removes all suggestions from all caches or internal stores in all
+  // providers. It does, however, not remove any suggestions from the provider's
+  // sources, so if their configuration hasn't changed, they should return the
+  // same results when they fetch the next time. In particular, calling this
+  // method will not mark any suggestions as discarded.
+  void ClearCachedSuggestions();
+
+  // Only for debugging use through the internals page. Some providers
+  // internally store a list of discarded suggestions to prevent them from
+  // reappearing. This function clears all such lists in all providers, making
+  // discarded suggestions reappear (only for certain providers).
+  void ClearDiscardedSuggestions();
+
+  // Discards the suggestion with the given |suggestion_id|, if it exists.
+  void Discard(ContentSuggestionsProviderType provider_type,
+               const std::string& suggestion_id);
+
+  // Observer accessors.
+  void AddObserver(ContentSuggestionsServiceObserver* observer);
+  void RemoveObserver(ContentSuggestionsServiceObserver* observer);
+
+  // Registers a new ContentSuggestionsProvider. This method will fail when a

[Marc Treib, 2016/06/28 15:04:55]

nit: s/when/if

[Philipp Keck, 2016/06/30 09:35:35]

Done.

+  // provider of the same type is already registered.
+  void RegisterProvider(ContentSuggestionsProvider* provider);
+
+  // For use by the snippets-internals page only.
+  const std::map<ContentSuggestionsProviderType, ContentSuggestionsProvider*>&
+  providers() const {
+    return providers_;
+  }
+
+ private:
+  // When |enabled_| is true the service will retrieve suggestions from the
+  // providers.
+  bool enabled_;
+
+  // All current suggestions.
+  std::map<ContentSuggestionCategory, std::vector<ContentSuggestion>>
+      suggestions_by_category_;
+
+  std::map<ContentSuggestionsProviderType, ContentSuggestionsProvider*>
+      providers_;
+
+  // The observers.
+  base::ObserverList<ContentSuggestionsServiceObserver> observers_;
+
+  // Implementation of ContentSuggestionsProvider::Delegate.
+  void OnSuggestionsChanged(
+      const ContentSuggestionsProvider& source,
+      ContentSuggestionCategory changed_category,
+      std::vector<ContentSuggestion> suggestions) override;
+
+  void OnProviderShutdown(const ContentSuggestionsProvider& source) override;
+
+  DISALLOW_COPY_AND_ASSIGN(ContentSuggestionsService);
+};
+
+class ContentSuggestionsServiceObserver {
+ public:
+  // Fired every time the service loads a new set of data. This event is fired
+  // per |changed_category|. The new data is then available through
+  // |suggestions()[changed_category]|.
+  virtual void OnSuggestionsChanged(
+      ContentSuggestionCategory changed_category) = 0;

[Marc Treib, 2016/06/28 15:04:55]

Hm, does this even need to include the category? At least for now, the UI
doesn't care, it'll update everything or nothing anyway.

[Philipp Keck, 2016/06/30 09:35:35]

Done.

+
+  // Sent when the service is shutting down.
+  virtual void ContentSuggestionsServiceShutdown() = 0;
+
+ protected:
+  virtual ~ContentSuggestionsServiceObserver() {}
+};
+
+}  // namespace ntp_snippets
+
+#endif  // COMPONENTS_NTP_SNIPPETS_CONTENT_SUGGESTIONS_SERVICE_H_