Install delegates for preload Tab.

ios/chrome/browser/ui/browser_view_controller.mm

Index: ios/chrome/browser/ui/browser_view_controller.mm
diff --git a/ios/chrome/browser/ui/browser_view_controller.mm b/ios/chrome/browser/ui/browser_view_controller.mm
index 2e19aae819b4c2b6f7d77518793d0ed4bb535692..a67591f0b82b08171db7924a2adf54c8fdf51506 100644
--- a/ios/chrome/browser/ui/browser_view_controller.mm
+++ b/ios/chrome/browser/ui/browser_view_controller.mm
@@ -4479,6 +4479,8 @@ class BrowserBookmarkModelBridge : public bookmarks::BookmarkModelObserver {
     didReplaceTab:(Tab*)oldTab
           withTab:(Tab*)newTab
           atIndex:(NSUInteger)index {
+  [self installDelegatesForTab:newTab];
+
   // Add |newTab|'s view to the hierarchy if it's the current Tab.
   if (self.active && model.currentTab == newTab)
     [self displayTab:newTab isNewSelection:NO];