Adding close button in SigninPromoView

ios/chrome/browser/ui/bookmarks/bookmark_folder_collection_view.mm

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/chrome/browser/ui/bookmarks/bookmark_folder_collection_view.h"
 
 #include "base/logging.h"
 #include "base/strings/sys_string_conversions.h"
 #include "components/bookmarks/browser/bookmark_model.h"
 #include "ios/chrome/browser/bookmarks/bookmarks_utils.h"
@@ skipping 396 matching lines @@
 - (UICollectionViewCell*)cellAtIndexPath:(NSIndexPath*)indexPath {
   if (indexPath.section == self.promoSection) {
     if (experimental_flags::IsSigninPromoEnabled()) {
       BookmarkSigninPromoCell* signinPromoCell = [self.collectionView
           dequeueReusableCellWithReuseIdentifier:[BookmarkSigninPromoCell
                                                      reuseIdentifier]
                                     forIndexPath:indexPath];
       signinPromoCell.signinPromoView.sendChromeCommand = YES;
       [[_signinPromoViewMediator createConfigurator]
           configureSigninPromoView:signinPromoCell.signinPromoView];
+      __weak BookmarkFolderCollectionView* weakSelf = self;
+      signinPromoCell.closeButtonAction = ^() {
+        [weakSelf.delegate bookmarkCollectionViewDismissPromo:self];
+      };
       return signinPromoCell;
     } else {
       BookmarkPromoCell* promoCell = [self.collectionView
           dequeueReusableCellWithReuseIdentifier:[BookmarkPromoCell
                                                      reuseIdentifier]
                                     forIndexPath:indexPath];
       promoCell.delegate = self;
       return promoCell;
     }
   }
@@ skipping 121 matching lines @@
       [NSIndexPath indexPathForRow:0 inSection:self.promoSection];
   BookmarkSigninPromoCell* signinPromoCell =
       static_cast<BookmarkSigninPromoCell*>(
           [self.collectionView cellForItemAtIndexPath:indexPath]);
   if (!signinPromoCell)
     return;
   [configurator configureSigninPromoView:signinPromoCell.signinPromoView];
 }
 
 @end