[iOS] Adds customSepartor to Settings

This CL enables customSeparator in Settings if the SettingsRefresh
flag is enable.

Bug: 922511
Change-Id: I119e37403c4161301e35982bb5733cee0497263c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2461327
Commit-Queue: Ewann Pellé <ewannpv@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815622}

ios/chrome/browser/ui/settings/settings_root_table_view_controller.mm

@@ -198,6 +198,18 @@ const CGFloat kActivityIndicatorDimensionIPhone = 56;
   return kDefaultHeaderFooterHeight;
 }
 
+#pragma mark - UITableViewDataSource
+
+- (UITableViewCell*)tableView:(UITableView*)tableView
+        cellForRowAtIndexPath:(NSIndexPath*)indexPath {
+  if (base::FeatureList::IsEnabled(kSettingsRefresh)) {
+    TableViewItem* item = [self.tableViewModel itemAtIndexPath:indexPath];
+    item.useCustomSeparator = YES;
+  }
+
+  return [super tableView:tableView cellForRowAtIndexPath:indexPath];
+}
+
 #pragma mark - TableViewLinkHeaderFooterItemDelegate
 
 - (void)view:(TableViewLinkHeaderFooterView*)view didTapLinkURL:(GURL)URL {