[iOS] Reduce Gap above Each Footnote in CBD

Reduce the gap above each footnote in the new Clear Browsing Data
Dialog by 5 pts, as suggested by UX.

Bug: 935346
Change-Id: Ie4263bbbcf41b6181517034429251ae29b7c596b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1609854Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Huanzhong Huang <huanzhong@chromium.org>
Cr-Commit-Position: refs/heads/master@{#660321}

ios/chrome/browser/ui/settings/clear_browsing_data/clear_browsing_data_table_view_controller.mm

@@ -270,6 +270,20 @@
 
 #pragma mark - UITableViewDelegate
 
+- (CGFloat)tableView:(UITableView*)tableView
+    heightForHeaderInSection:(NSInteger)section {
+  NSInteger sectionIdentifier =
+      [self.tableViewModel sectionIdentifierForSection:section];
+  switch (sectionIdentifier) {
+    case SectionIdentifierGoogleAccount:
+    case SectionIdentifierClearSyncAndSavedSiteData:
+    case SectionIdentifierSavedSiteData:
+      return 5;
+    default:
+      return [super tableView:tableView heightForHeaderInSection:section];
+  }
+}
+
 - (void)tableView:(UITableView*)tableView
     didSelectRowAtIndexPath:(NSIndexPath*)indexPath {
   if (!IsNewClearBrowsingDataUIEnabled()) {