[NTP Snippets] Persist the set of snippets in a pref

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 <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/sequenced_task_runner.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/ntp_snippets/inner_iterator.h"
 #include "components/ntp_snippets/ntp_snippet.h"
 #include "components/ntp_snippets/ntp_snippets_fetcher.h"
 #include "components/ntp_snippets/ntp_snippets_scheduler.h"
 
+class PrefService;
+
+namespace base {
+class FilePath;
+class ListValue;
+}
+
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
 namespace ntp_snippets {
 
 class NTPSnippetsServiceObserver;
 
 // Stores and vend fresh content data for the NTP.
 class NTPSnippetsService : public KeyedService, NTPSnippetsFetcher::Observer {
  public:
   using NTPSnippetStorage = std::vector<scoped_ptr<NTPSnippet>>;
   using const_iterator =
       InnerIterator<NTPSnippetStorage::const_iterator, const NTPSnippet>;
 
   // |application_language_code| should be a ISO 639-1 compliant string. Aka
   // '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 code.
-  NTPSnippetsService(scoped_refptr<base::SequencedTaskRunner> file_task_runner,
+  NTPSnippetsService(PrefService* pref_service,
+                     scoped_refptr<base::SequencedTaskRunner> file_task_runner,
                      const std::string& application_language_code,
                      NTPSnippetsScheduler* scheduler,
                      scoped_ptr<NTPSnippetsFetcher> snippets_fetcher);
   ~NTPSnippetsService() override;
 
+  static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
+
   void Init(bool enabled);
 
   // Fetches snippets from the server. |overwrite| is true if existing snippets
   // should be overwritten.
   void FetchSnippets(bool overwrite);
 
   // Inherited from KeyedService.
   void Shutdown() override;
 
   // True once the data is loaded in memory and available to loop over.
@@ skipping 19 matching lines @@
   const_iterator begin() {
     DCHECK(loaded_);
     return const_iterator(snippets_.begin());
   }
   const_iterator end() {
     DCHECK(loaded_);
     return const_iterator(snippets_.end());
   }
 
  private:
+  void OnSnippetsDownloaded(const base::FilePath& download_path);
   void OnFileReadDone(const std::string* json, bool success);
-  void OnSnippetsDownloaded(const base::FilePath& download_path);
 
-  // Expects the JSON to be a list of dictionaries with keys matching the
-  // properties of a snippet (url, title, site_title, etc...). The url is the
-  // only mandatory value.
+  // Expects a top-level dictionary containing a "recos" list, which will be
+  // passed to |LoadFromJSONList|.
   bool LoadFromJSONString(const std::string& str);
 
+  // Expects a list of dictionaries each containing a "contentInfo" dictionary
+  // with keys matching the properties of a  snippet (url, title, site_title,
+  // etc...). The url is the only mandatory value.
+  bool LoadFromJSONList(const base::ListValue& list);
+
+  // TODO(treib): Investigate a better storage, maybe LevelDB or SQLite?
+  void LoadFromPrefs();
+  void StoreToPrefs();
+
+  PrefService* pref_service_;
+
   // True if the suggestions are loaded.
   bool loaded_;
 
   // The SequencedTaskRunner on which file system operations will be run.
   scoped_refptr<base::SequencedTaskRunner> file_task_runner_;
 
   // All the suggestions.
   NTPSnippetStorage snippets_;
 
   // The ISO 639-1 code of the language used by the application.
@@ skipping 30 matching lines @@
   // Send when the service is shutting down.
   virtual void NTPSnippetsServiceShutdown(NTPSnippetsService* service) = 0;
 
  protected:
   virtual ~NTPSnippetsServiceObserver() {}
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_SERVICE_H_