Make image_decoder a Leaky LazyInstance

chrome/browser/chromeos/login/users/avatar/user_image_loader.h

Index: chrome/browser/chromeos/login/users/avatar/user_image_loader.h
diff --git a/chrome/browser/chromeos/login/users/avatar/user_image_loader.h b/chrome/browser/chromeos/login/users/avatar/user_image_loader.h
index 10c7be458e2e89630835d0ca95f05666b40e3a52..2d00ba0df54dcef50a9c248fa18e77287fffefee 100644
--- a/chrome/browser/chromeos/login/users/avatar/user_image_loader.h
+++ b/chrome/browser/chromeos/login/users/avatar/user_image_loader.h
@@ -5,7 +5,7 @@
 #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>

[dcheng, 2015/03/23 11:52:09]

I think you can remove this #include.

[Theresa, 2015/03/23 17:33:09]

Done.

 #include <string>
 
 #include "base/callback.h"
@@ -27,8 +27,7 @@ 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)>
@@ -67,9 +66,27 @@ class UserImageLoader : public base::RefCountedThreadSafe<UserImageLoader>,
     const LoadedCallback loaded_cb;
   };
 
-  typedef std::map<const ImageDecoder*, ImageInfo> ImageInfoMap;
+  class UserImageRequest : public ImageDecoder::ImageRequest {
+   public:
+    UserImageRequest(const ImageInfo& image_info,
+                     const std::string& image_data,
+                     UserImageLoader* user_image_loader);
 
-  ~UserImageLoader() override;
+    // ImageDecoder::ImageRequest implementation. These callbacks will only be
+    // invoked

[dcheng, 2015/03/23 11:52:08]

This comment needs to be updated / rewrapped.

[Theresa, 2015/03/23 17:33:09]

I rewrapped. I think the comment is still accurate, though. What did you think
should be updated?

[dcheng, 2015/03/24 05:18:18]

This class has no background_task_runner_ member itself, so it might be a bit
confusing to reference it.

[Theresa, 2015/03/24 23:51:42]

Done.

+    // via the |background_task_runner_|.
+    void OnImageDecoded(const SkBitmap& decoded_image) override;
+    void OnDecodeImageFailed() override;
+
+    const ImageInfo image_info_;

[dcheng, 2015/03/23 11:52:08]

Convention is to make these private and use accessors.

[Theresa, 2015/03/23 17:33:09]

Done.

+    std::vector<unsigned char> image_data_;

[dcheng, 2015/03/23 11:52:08]

Having to copy this is pretty sad. But I don't see a good way around it, given
the new interface...

[Theresa, 2015/03/23 17:33:09]

Acknowledged.

+    UserImageLoader* user_image_loader_;
+
+   private:
+    ~UserImageRequest() 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_|.
@@ -80,12 +97,6 @@ class UserImageLoader : public base::RefCountedThreadSafe<UserImageLoader>,
   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_;
@@ -97,10 +108,6 @@ class UserImageLoader : public base::RefCountedThreadSafe<UserImageLoader>,
   // 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);
 };