Implement manifest icon downloader

chrome/browser/android/webapps/add_to_homescreen_data_fetcher.h

Index: chrome/browser/android/webapps/add_to_homescreen_data_fetcher.h
diff --git a/chrome/browser/android/webapps/add_to_homescreen_data_fetcher.h b/chrome/browser/android/webapps/add_to_homescreen_data_fetcher.h
index d3af3ac1c0f8b7198f3d36d439046c2de4646e38..18a41733c506c08bb216c30d5ebe40e3b21234b9 100644
--- a/chrome/browser/android/webapps/add_to_homescreen_data_fetcher.h
+++ b/chrome/browser/android/webapps/add_to_homescreen_data_fetcher.h
@@ -82,13 +82,9 @@ class AddToHomescreenDataFetcher
   void CreateLauncherIcon(
       const favicon_base::FaviconRawBitmapResult& bitmap_result);
 
-  // Callback run after an attempt to download manifest icon has been made.  May
-  // kick off the download of a favicon if it failed.
-  void OnManifestIconFetched(int id,
-                             int http_status_code,
-                             const GURL& url,
-                             const std::vector<SkBitmap>& bitmaps,
-                             const std::vector<gfx::Size>& sizes);
+  // Callback run after an attempt to download manifest icon has been made. May
+  // kick off the download of a favicon if it failed (i.e. the bitmap is empty).
+  void OnManifestIconFetched(const SkBitmap& icon);
 
   // Notifies the observer that the shortcut data is all available.
   void NotifyObserver(const SkBitmap& icon);