Fetch snippets from ChromeReader and show them on the NTP

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/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"
 
 namespace ntp_snippets {
 
 class NTPSnippetsServiceObserver;
 
 // Stores and vend fresh content data for the NTP.
-class NTPSnippetsService : public KeyedService {
+class NTPSnippetsService : public KeyedService, NTPSnippetsFetcher::Observer {
  public:
   using NTPSnippetStorage = std::vector<std::unique_ptr<NTPSnippet>>;

[Bernhard Bauer, 2016/02/08 18:19:27]

This should use scoped_ptr, not std::unique_ptr.

[May, 2016/02/09 17:38:54]

Why should it be a scoped_ptr? We construct the NTPSnippetObject in NTPSnippet
class and then this class claims ownership of it here.

[Marc Treib, 2016/02/10 10:44:43]

scoped_ptr and unique_ptr are essentially the same thing, but unique_ptr is a
C++11 feature that's not allowed yet.

[Bernhard Bauer, 2016/02/10 10:48:44]

Yup, but it's just that we usually use scoped_ptr in Chrome to express that
notion of ownership.

[May, 2016/02/10 18:16:46]

Done.

   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.
-  explicit NTPSnippetsService(const std::string& application_language_code);
+  explicit NTPSnippetsService(

[Bernhard Bauer, 2016/02/08 18:19:27]

`explicit` is only necessary for single-argument constructors.

[May, 2016/02/09 17:38:54]

Done.

+      scoped_refptr<base::SequencedTaskRunner> file_task_runner,
+      const std::string& application_language_code,
+      NTPSnippetsFetcher* snippets_fetcher);
   ~NTPSnippetsService() override;
 
+  // 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.
   bool is_loaded() { return loaded_; }
 
   // Observer accessors.
   void AddObserver(NTPSnippetsServiceObserver* observer);
   void RemoveObserver(NTPSnippetsServiceObserver* observer);
 
@@ skipping 17 matching lines @@
   //  }
   const_iterator begin() {
     DCHECK(loaded_);
     return const_iterator(snippets_.begin());
   }
   const_iterator end() {
     DCHECK(loaded_);
     return const_iterator(snippets_.end());
   }
 
+  // NTPSnippetsFetcher::Observer overrides:
+  void OnNTPSnippetsDownloaded();

[Bernhard Bauer, 2016/02/08 18:19:27]

If this really overrides a method, it should have the `override` modifier. Why
doesn't a compiler complain about this?

[May, 2016/02/09 17:38:54]

No idea why it didn't complain. But anyway I removed it in favor a callback list

+
  private:
+  void OnFileReadDone(std::string& json);

[Marc Treib, 2016/02/09 09:17:54]

const std::string&

[May, 2016/02/09 17:38:54]

Done.

+
   // 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.
   const std::string application_language_code_;
+
   // The observers.
   base::ObserverList<NTPSnippetsServiceObserver> observers_;
 
+  // The snippets fetcher
+  scoped_ptr<NTPSnippetsFetcher> snippets_fetcher_;
+
   DISALLOW_COPY_AND_ASSIGN(NTPSnippetsService);
 };
 
 class NTPSnippetsServiceObserver {
  public:
   // Send everytime the service loads a new set of data.
   virtual void NTPSnippetsServiceLoaded(NTPSnippetsService* service) = 0;
   // 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_