Refactor Reading List Model to use URL as key.

ios/chrome/browser/reading_list/reading_list_download_service.h

Index: ios/chrome/browser/reading_list/reading_list_download_service.h
diff --git a/ios/chrome/browser/reading_list/reading_list_download_service.h b/ios/chrome/browser/reading_list/reading_list_download_service.h
index f8bc288227e34d1934159af6f58407e3339a6dba..fa8d890d53ffd7608f314ce58555fe598a7e4e07 100644
--- a/ios/chrome/browser/reading_list/reading_list_download_service.h
+++ b/ios/chrome/browser/reading_list/reading_list_download_service.h
@@ -46,14 +46,10 @@ class ReadingListDownloadService
 
   // ReadingListModelObserver implementation
   void ReadingListModelLoaded(const ReadingListModel* model) override;
-  void ReadingListWillRemoveReadEntry(const ReadingListModel* model,
-                                      size_t index) override;
-  void ReadingListWillRemoveUnreadEntry(const ReadingListModel* model,
-                                        size_t index) override;
-  void ReadingListWillAddUnreadEntry(const ReadingListModel* model,
-                                     const ReadingListEntry& entry) override;
-  void ReadingListWillAddReadEntry(const ReadingListModel* model,
-                                   const ReadingListEntry& entry) override;
+  void ReadingListWillRemoveEntry(const ReadingListModel* model,
+                                  const GURL& url) override;
+  void ReadingListWillAddEntry(const ReadingListModel* model,
+                               const ReadingListEntry& entry) override;
 
  private:
   // Tries to save offline versions of all entries in the reading list that are