Implement first version of OfflinePageSuggestionsProvider

components/ntp_snippets/offline_pages/offline_page_suggestions_provider.h

Index: components/ntp_snippets/offline_pages/offline_page_suggestions_provider.h
diff --git a/components/ntp_snippets/offline_pages/offline_page_suggestions_provider.h b/components/ntp_snippets/offline_pages/offline_page_suggestions_provider.h
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+// 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_OFFLINE_PAGES_OFFLINE_PAGE_SUGGESTIONS_PROVIDER_H_
+#define COMPONENTS_NTP_SNIPPETS_OFFLINE_PAGES_OFFLINE_PAGE_SUGGESTIONS_PROVIDER_H_
+
+#include <string>
+#include <vector>
+
+#include "base/callback_forward.h"
+#include "components/keyed_service/core/keyed_service.h"
+#include "components/ntp_snippets/content_suggestion.h"
+#include "components/ntp_snippets/content_suggestions_category.h"
+#include "components/ntp_snippets/content_suggestions_category_status.h"
+#include "components/ntp_snippets/content_suggestions_provider.h"
+#include "components/offline_pages/offline_page_model.h"
+#include "components/offline_pages/offline_page_types.h"
+
+namespace gfx {
+class Image;
+}
+
+namespace ntp_snippets {
+
+// Provides content suggestions from the offline pages model.
+// Currently, those are only the pages that the user last navigated to in an
+// open tab and offlined bookmarks.
+class OfflinePageSuggestionsProvider
+    : public KeyedService,
+      public ContentSuggestionsProvider,
+      public offline_pages::OfflinePageModel::Observer {
+ public:
+  OfflinePageSuggestionsProvider(
+      offline_pages::OfflinePageModel* offline_page_model);
+  ~OfflinePageSuggestionsProvider() override;
+
+  // Inherited from KeyedService.
+  void Shutdown() override;
+
+ private:
+  // ContentSuggestionsProvider implementation.
+  void SetObserver(ContentSuggestionsProvider::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;
+
+  // OfflinePageModel::Observer implementation.
+  void OfflinePageModelLoaded(offline_pages::OfflinePageModel* model) override;
+  void OfflinePageModelChanged(offline_pages::OfflinePageModel* model) override;
+  void OfflinePageDeleted(int64_t offline_id,
+                          const offline_pages::ClientId& client_id) override;
+
+  // Queries the OfflinePageModel for offline pages.
+  void FetchOfflinePages();
+
+  // Callback from the OfflinePageModel.
+  void OnOfflinePagesLoaded(
+      const offline_pages::MultipleOfflinePageItemResult& result);
+
+  // Updates the |category_status_| and notifies the |observer_|, if necessary.
+  void NotifyStatusChanged(ContentSuggestionsCategoryStatus new_status);
+
+  ContentSuggestionsCategoryStatus category_status_;
+
+  ContentSuggestionsProvider::Observer* observer_;
+
+  offline_pages::OfflinePageModel* offline_page_model_;
+
+  DISALLOW_COPY_AND_ASSIGN(OfflinePageSuggestionsProvider);
+};
+
+}  // namespace ntp_snippets
+
+#endif  // COMPONENTS_NTP_SNIPPETS_OFFLINE_PAGES_OFFLINE_PAGE_SUGGESTIONS_PROVIDER_H_