[NTP Snippets] Cache images in a LevelDB

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/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "base/scoped_observer.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/ntp_snippet.h"
 #include "components/ntp_snippets/ntp_snippets_fetcher.h"
 #include "components/ntp_snippets/ntp_snippets_scheduler.h"
 #include "components/suggestions/suggestions_service.h"
 #include "components/sync_driver/sync_service_observer.h"
 
 class PrefRegistrySimple;
 class PrefService;
 
 namespace base {
+class RefCountedMemory;
 class Value;
 }
 
 namespace gfx {
 class Image;
 }
 
 namespace image_fetcher {
+class ImageDecoder;
 class ImageFetcher;
 }
 
 namespace suggestions {
 class SuggestionsProfile;
 }
 
 namespace sync_driver {
 class SyncService;
 }
 
 namespace ntp_snippets {
 
 enum class DisabledReason {
   // Snippets are enabled
   NONE,
   // Snippets have been disabled as part of the service configuration.
   EXPLICITLY_DISABLED,
   // History sync is not enabled, and the service requires it to be enabled.
   HISTORY_SYNC_DISABLED,
   // The sync service is not completely initialized, and the status is unknown.
   HISTORY_SYNC_STATE_UNKNOWN
 };
 
 class NTPSnippetsDatabase;
 class NTPSnippetsServiceObserver;
 
 // Stores and vends fresh content data for the NTP.
 class NTPSnippetsService : public KeyedService,
-                           public sync_driver::SyncServiceObserver {
+                           public sync_driver::SyncServiceObserver,
+                           public image_fetcher::ImageFetcherDelegate {
  public:
   using ImageFetchedCallback =
       base::Callback<void(const std::string& snippet_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,
                      sync_driver::SyncService* sync_service,
                      suggestions::SuggestionsService* suggestions_service,
                      const std::string& application_language_code,
                      NTPSnippetsScheduler* scheduler,
                      std::unique_ptr<NTPSnippetsFetcher> snippets_fetcher,
                      std::unique_ptr<image_fetcher::ImageFetcher> image_fetcher,
+                     std::unique_ptr<image_fetcher::ImageDecoder> image_decoder,
                      std::unique_ptr<NTPSnippetsDatabase> database);
   ~NTPSnippetsService() override;
 
   static void RegisterProfilePrefs(PrefRegistrySimple* registry);
 
   // Inherited from KeyedService.
   void Shutdown() override;
 
   // Returns whether the service is ready. While this is false, the list of
   // snippets will be empty, and all modifications to it (fetch, discard, etc)
@@ skipping 95 matching lines @@
     DISABLED,
 
     // The service shutdown and can't be used anymore. This state is checked
     // for early exit in callbacks from observers.
     SHUT_DOWN
   };
 
   // sync_driver::SyncServiceObserver implementation.
   void OnStateChanged() override;
 
+  // image_fetcher::ImageFetcherDelegate implementation.
+  void OnImageDataFetched(const std::string& snippet_id,
+                          const std::string& image_data) override;
+
   // Callback for the NTPSnippetsDatabase.
   void OnDatabaseLoaded(NTPSnippet::PtrVector snippets);
 
   // Callback for the SuggestionsService.
   void OnSuggestionsChanged(const suggestions::SuggestionsProfile& suggestions);
 
   // Callback for the NTPSnippetsFetcher.
   void OnFetchFinished(NTPSnippetsFetcher::OptionalSnippets snippets);
 
   // Merges newly available snippets with the previously available list.
   void MergeSnippets(NTPSnippet::PtrVector new_snippets);
 
   std::set<std::string> GetSnippetHostsFromPrefs() const;
   void StoreSnippetHostsToPrefs(const std::set<std::string>& hosts);
 
   // Removes the expired snippets (including discarded) from the service and the
   // database, and schedules another pass for the next expiration.
   void ClearExpiredSnippets();
 
   // Completes the initialization phase of the service, registering the last
   // observers. This is done after construction, once the database is loaded.
   void FinishInitialization();
 
   void LoadingSnippetsFinished();
 
+  void OnSnippetImageFetchedFromDatabase(const std::string& snippet_id,
+                                         const ImageFetchedCallback& callback,
+                                         std::string data);
+
+  void OnSnippetImageDecoded(const std::string& snippet_id,
+                             const ImageFetchedCallback& callback,
+                             const gfx::Image& image);
+
+  void FetchSnippetImageFromNetwork(const std::string& snippet_id,
+                                    const ImageFetchedCallback& callback);
+
   // Returns whether the service should be enabled or disable depending on its
   // internal state and the state of its dependencies.
   State GetStateForDependenciesStatus();
 
   // Verifies state transitions (see |State|'s documentation) and applies them.
   // Does nothing if called with the current state.
   void EnterState(State state);
 
   // Enables the service and triggers a fetch if required. Do not call directly,
   // use |EnterState| instead.
@@ skipping 50 matching lines @@
       suggestions::SuggestionsService::ResponseCallbackList::Subscription;
   std::unique_ptr<SuggestionsSubscription> suggestions_service_subscription_;
 
   // The snippets fetcher.
   std::unique_ptr<NTPSnippetsFetcher> snippets_fetcher_;
 
   // Timer that calls us back when the next snippet expires.
   base::OneShotTimer expiry_timer_;
 
   std::unique_ptr<image_fetcher::ImageFetcher> image_fetcher_;
+  std::unique_ptr<image_fetcher::ImageDecoder> image_decoder_;
 
   // The database for persisting snippets.
   std::unique_ptr<NTPSnippetsDatabase> database_;
 
   // 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);
 };
 
 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 service has been disabled. Can be from explicit user action
   // or because a requirement (e.g. History Sync) is not fulfilled anymore.
   virtual void NTPSnippetsServiceDisabled() = 0;
 
  protected:
   virtual ~NTPSnippetsServiceObserver() {}
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_SERVICE_H_