Make image_decoder a Leaky LazyInstance

chrome/browser/chromeos/login/users/avatar/user_image_loader.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 CHROME_BROWSER_CHROMEOS_LOGIN_USERS_AVATAR_USER_IMAGE_LOADER_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_USERS_AVATAR_USER_IMAGE_LOADER_H_
 
-#include <map>
+#include <queue>
 #include <string>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/image_decoder.h"
 
 class SkBitmap;
 
 namespace base {
 class SequencedTaskRunner;
 }
 
 namespace user_manager {
 class UserImage;
 }
 
 namespace chromeos {
 
 // Helper that reads, decodes and optionally resizes an image on a background
 // thread. Returns the image in the form of an SkBitmap.
-class UserImageLoader : public base::RefCountedThreadSafe<UserImageLoader>,
-                        public ImageDecoder::Delegate {
+class UserImageLoader : public base::RefCountedThreadSafe<UserImageLoader> {
  public:
   // Callback used to return the result of an image load operation.
   typedef base::Callback<void(const user_manager::UserImage& user_image)>
       LoadedCallback;
 
   // All file I/O, decoding and resizing are done via |background_task_runner|.
   UserImageLoader(
       ImageDecoder::ImageCodec image_codec,
       scoped_refptr<base::SequencedTaskRunner> background_task_runner);
 
@@ skipping 18 matching lines @@
     ImageInfo(const std::string& file_path,
               int pixels_per_side,
               const LoadedCallback& loaded_cb);
     ~ImageInfo();
 
     const std::string file_path;
     const int pixels_per_side;
     const LoadedCallback loaded_cb;
   };
 
-  typedef std::map<const ImageDecoder*, ImageInfo> ImageInfoMap;
+  class ImageRequest : public ImageDecoder::Delegate {
+   public:
+    ImageRequest(const ImageInfo& image_info,
+                 const std::string& image_data,
+                 UserImageLoader* user_image_loader);
 
-  ~UserImageLoader() override;
+    // ImageDecoder::Delegate implementation. These callbacks will only be
+    // invoked
+    // via the |background_task_runner_|.
+    void OnImageDecoded(const SkBitmap& decoded_image) override;
+    void OnDecodeImageFailed() override;
+
+    const ImageInfo image_info_;
+    std::vector<unsigned char> image_data_;
+    UserImageLoader* user_image_loader_;
+
+   private:
+    ~ImageRequest() override;
+  };
+
+  ~UserImageLoader();
 
   // Reads the image from |image_info.file_path| and starts the decoding
   // process. This method may only be invoked via the |background_task_runner_|.
   void ReadAndDecodeImage(const ImageInfo& image_info);
 
   // Decodes the image |data|. This method may only be invoked via the
   // |background_task_runner_|.
   void DecodeImage(const scoped_ptr<std::string> data,
                    const ImageInfo& image_info);
 
-  // ImageDecoder::Delegate implementation. These callbacks will only be invoked
-  // via the |background_task_runner_|.
-  void OnImageDecoded(const ImageDecoder* decoder,
-                      const SkBitmap& decoded_image) override;
-  void OnDecodeImageFailed(const ImageDecoder* decoder) override;
-
   // The foreground task runner on which |this| is instantiated, Start() is
   // called and LoadedCallbacks are invoked.
   scoped_refptr<base::SequencedTaskRunner> foreground_task_runner_;
 
   // The background task runner on which file I/O, image decoding and resizing
   // are done.
   scoped_refptr<base::SequencedTaskRunner> background_task_runner_;
 
   // Specify how the file should be decoded in the utility process.
   const ImageDecoder::ImageCodec image_codec_;
 
-  // Holds information about the images currently being decoded. Accessed via
-  // |background_task_runner_| only.
-  ImageInfoMap image_info_map_;
-
   DISALLOW_COPY_AND_ASSIGN(UserImageLoader);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_USERS_AVATAR_USER_IMAGE_LOADER_H_