Convert TabModelTest to use the public API of TabModel.

ios/chrome/browser/tabs/tab_model.mm

 // Copyright 2012 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/tabs/tab_model.h"
 
 #include <cstdint>
 #include <utility>
 #include <vector>
 
@@ skipping 955 matching lines @@
 }
 
 // Called when UIApplicationWillEnterForegroundNotification is received.
 - (void)applicationWillEnterForeground:(NSNotification*)notify {
   if (_tabUsageRecorder) {
     _tabUsageRecorder->AppWillEnterForeground();
   }
 }
 
 @end
-
-@implementation TabModel (PrivateForTestingOnly)
-
-- (Tab*)addTabWithURL:(const GURL&)URL referrer:(const web::Referrer&)referrer {
-  return [self insertTabWithURL:URL
-                       referrer:referrer
-                         opener:nil
-                        atIndex:self.count];
-}
-
-- (Tab*)insertTabWithURL:(const GURL&)URL
-                referrer:(const web::Referrer&)referrer
-                  opener:(Tab*)parentTab
-                 atIndex:(NSUInteger)index {
-  DCHECK(_browserState);
-  base::scoped_nsobject<Tab> tab([[Tab alloc] initWithBrowserState:_browserState
-                                                            opener:parentTab
-                                                       openedByDOM:NO
-                                                             model:self]);
-  web::NavigationManager::WebLoadParams params(URL);
-  params.referrer = referrer;
-  params.transition_type = ui::PAGE_TRANSITION_TYPED;
-  [[tab webController] loadWithParams:params];
-  [tab webController].webUsageEnabled = webUsageEnabled_;
-  [self insertTab:tab atIndex:index opener:parentTab];
-  return tab;
-}
-
-@end