Decode ImageManager cached images on demand.

components/suggestions/image_manager.h

 // Copyright 2014 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_SUGGESTIONS_IMAGE_MANAGER_H_
 #define COMPONENTS_SUGGESTIONS_IMAGE_MANAGER_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/containers/hash_tables.h"
+#include "base/memory/ref_counted_memory.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/task_runner.h"
 #include "base/threading/thread_checker.h"
 #include "components/leveldb_proto/proto_database.h"
 #include "components/suggestions/image_fetcher_delegate.h"
 #include "components/suggestions/proto/suggestions.pb.h"
 #include "ui/gfx/image/image_skia.h"
 #include "url/gurl.h"
 
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace suggestions {
 
 class ImageData;
 class ImageFetcher;
 class SuggestionsProfile;
 
 // A class used to fetch server images asynchronously and manage the caching
 // layer (both in memory and on disk).
 class ImageManager : public ImageFetcherDelegate {
  public:
   typedef std::vector<ImageData> ImageDataVector;
 
   ImageManager(scoped_ptr<ImageFetcher> image_fetcher,
-               scoped_ptr<leveldb_proto::ProtoDatabase<ImageData> > database,
-               const base::FilePath& database_dir);
+               scoped_ptr<leveldb_proto::ProtoDatabase<ImageData>> database,
+               const base::FilePath& database_dir,
+               scoped_refptr<base::TaskRunner> background_task_runner);
   ~ImageManager() override;
 
   virtual void Initialize(const SuggestionsProfile& suggestions);
 
   // Should be called from the UI thread.
   virtual void GetImageForURL(
       const GURL& url,
       base::Callback<void(const GURL&, const SkBitmap*)> callback);
 
  protected:
   // Perform additional tasks when an image has been fetched.
   void OnImageFetched(const GURL& url, const SkBitmap* bitmap) override;
 
  private:
   friend class MockImageManager;
   friend class ImageManagerTest;
   FRIEND_TEST_ALL_PREFIXES(ImageManagerTest, InitializeTest);
   FRIEND_TEST_ALL_PREFIXES(ImageManagerTest, GetImageForURLNetworkCacheHit);
   FRIEND_TEST_ALL_PREFIXES(ImageManagerTest,
                            GetImageForURLNetworkCacheNotInitialized);
 
   // Used for testing.
   ImageManager();
 
   typedef std::vector<base::Callback<void(const GURL&, const SkBitmap*)> >
       CallbackVector;
-  typedef base::hash_map<std::string, SkBitmap> ImageMap;
+  typedef base::hash_map<std::string, scoped_refptr<base::RefCountedMemory>>
+      ImageMap;
 
   // State related to an image fetch (associated website url, image_url,
   // pending callbacks).
   struct ImageCacheRequest {
     ImageCacheRequest();
     ~ImageCacheRequest();
 
     GURL url;
     GURL image_url;
     // Queue for pending callbacks, which may accumulate while the request is in
     // flight.
     CallbackVector callbacks;
   };
 
   typedef std::map<const GURL, ImageCacheRequest> ImageCacheRequestMap;
 
   // Looks up image URL for |url|. If found, writes the result to |image_url|
   // and returns true. Otherwise just returns false.
   bool GetImageURL(const GURL& url, GURL* image_url);
 
   void QueueCacheRequest(
       const GURL& url, const GURL& image_url,
       base::Callback<void(const GURL&, const SkBitmap*)> callback);
 
   void ServeFromCacheOrNetwork(
       const GURL& url, const GURL& image_url,
       base::Callback<void(const GURL&, const SkBitmap*)> callback);
 
-  // Will return false if no bitmap was found corresponding to |url|, else
-  // return true and call |callback| with the found bitmap.
-  bool ServeFromCache(
+  void OnCacheImageDecoded(
       const GURL& url,
-      base::Callback<void(const GURL&, const SkBitmap*)> callback);
+      const GURL& image_url,
+      base::Callback<void(const GURL&, const SkBitmap*)> callback,
+      scoped_ptr<SkBitmap> bitmap);
 
   // Returns null if the |url| had no entry in the cache.
-  SkBitmap* GetBitmapFromCache(const GURL& url);
+  scoped_refptr<base::RefCountedMemory> GetEncodedImageFromCache(
+      const GURL& url);
 
   // Save the image bitmap in the cache and in the database.
   void SaveImage(const GURL& url, const SkBitmap& bitmap);
 
   // Database callback methods.
   // Will initiate loading the entries.
   void OnDatabaseInit(bool success);
   // Will transfer the loaded |entries| in memory (|image_map_|).
   void OnDatabaseLoad(bool success, scoped_ptr<ImageDataVector> entries);
   void OnDatabaseSave(bool success);
@@ skipping 11 matching lines @@
   // requests while the database hasn't loaded.
   ImageCacheRequestMap pending_cache_requests_;
 
   // Holding the bitmaps in memory, keyed by website URL string.
   ImageMap image_map_;
 
   scoped_ptr<ImageFetcher> image_fetcher_;
 
   scoped_ptr<leveldb_proto::ProtoDatabase<ImageData> > database_;
 
+  scoped_refptr<base::TaskRunner> background_task_runner_;
+
   bool database_ready_;
 
   base::ThreadChecker thread_checker_;
 
   base::WeakPtrFactory<ImageManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageManager);
 };
 
 }  // namespace suggestions
 
 #endif  // COMPONENTS_SUGGESTIONS_IMAGE_MANAGER_H_