arc: Do not keep track of in-flight decode requests.

chrome/browser/chromeos/arc/arc_wallpaper_handler.h

Index: chrome/browser/chromeos/arc/arc_wallpaper_handler.h
diff --git a/chrome/browser/chromeos/arc/arc_wallpaper_handler.h b/chrome/browser/chromeos/arc/arc_wallpaper_handler.h
index cb4b96d65158066d7d6720de953a5c58bb00b389..fee23547c5dde427a6d377adc00f69bd532884c5 100644
--- a/chrome/browser/chromeos/arc/arc_wallpaper_handler.h
+++ b/chrome/browser/chromeos/arc/arc_wallpaper_handler.h
@@ -12,6 +12,7 @@
 #include <vector>
 
 #include "base/macros.h"
+#include "chrome/browser/image_decoder.h"
 #include "components/arc/set_wallpaper_delegate.h"
 
 class SkBitmap;
@@ -19,7 +20,8 @@ class SkBitmap;
 namespace arc {
 
 // Lives on the UI thread.
-class ArcWallpaperHandler : public SetWallpaperDelegate {
+class ArcWallpaperHandler : public SetWallpaperDelegate,
+                            public ImageDecoder::ImageRequest {
  public:
   ArcWallpaperHandler();
   ~ArcWallpaperHandler() override;
@@ -27,16 +29,11 @@ class ArcWallpaperHandler : public SetWallpaperDelegate {
   // SetWallpaperDelegate implementation.
   void SetWallpaper(const std::vector<uint8_t>& jpeg_data) override;
 
- private:
-  class ImageRequestImpl;
-
-  // Called from ImageRequestImpl on decode completion.
-  void OnImageDecoded(ImageRequestImpl* request, const SkBitmap& bitmap);
-  void OnDecodeImageFailed(ImageRequestImpl* request);
-
-  // The set of in-flight decode requests.
-  std::set<std::unique_ptr<ImageRequestImpl>> inflight_requests_;
+  // ImageDecoder::ImageRequest implementation.
+  void OnImageDecoded(const SkBitmap& bitmap) override;
+  void OnDecodeImageFailed() override;
 
+ private:
   DISALLOW_COPY_AND_ASSIGN(ArcWallpaperHandler);
 };