Remove usage of FOR_EACH_OBSERVER macro in ios/

ios/chrome/browser/reading_list/reading_list_model.cc

Index: ios/chrome/browser/reading_list/reading_list_model.cc
diff --git a/ios/chrome/browser/reading_list/reading_list_model.cc b/ios/chrome/browser/reading_list/reading_list_model.cc
index 073ec3b759bcd874dbe77596632d27bf012f54d7..3407c0eb648a20738597c405d5ec4bab7463c57f 100644
--- a/ios/chrome/browser/reading_list/reading_list_model.cc
+++ b/ios/chrome/browser/reading_list/reading_list_model.cc
@@ -32,8 +32,8 @@ ReadingListModel::BeginBatchUpdates() {
 
   ++current_batch_updates_count_;
   if (current_batch_updates_count_ == 1) {
-    FOR_EACH_OBSERVER(ReadingListModelObserver, observers_,
-                      ReadingListModelBeganBatchUpdates(this));
+    for (auto& observer : observers_)
+      observer.ReadingListModelBeganBatchUpdates(this);
   }
   return token;
 }
@@ -42,7 +42,7 @@ void ReadingListModel::EndBatchUpdates() {
   DCHECK(IsPerformingBatchUpdates());
   --current_batch_updates_count_;
   if (current_batch_updates_count_ == 0) {
-    FOR_EACH_OBSERVER(ReadingListModelObserver, observers_,
-                      ReadingListModelCompletedBatchUpdates(this));
+    for (auto& observer : observers_)
+      observer.ReadingListModelCompletedBatchUpdates(this);
   }
 }