Refactor TabModel to use WebStateList to store WebStates.

ios/chrome/browser/tabs/tab_model_order_controller_unittest.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.
 
 #include "base/mac/scoped_nsautorelease_pool.h"
 #include "base/memory/ptr_util.h"
 #include "ios/chrome/browser/browser_state/test_chrome_browser_state.h"
 #include "ios/chrome/browser/browser_state/test_chrome_browser_state_manager.h"
 #import "ios/chrome/browser/sessions/session_window.h"
 #import "ios/chrome/browser/sessions/test_session_service.h"
@@ skipping 68 matching lines @@
                          atIndex:TabModelConstants::kTabPositionAutomatically
                     inBackground:YES];
   }
 
   GURL url_;
   web::Referrer referrer_;
   web::TestWebThreadBundle thread_bundle_;
   IOSChromeScopedTestingChromeBrowserStateManager scoped_browser_state_manager_;
   base::scoped_nsobject<SessionWindowIOS> sessionWindow_;
   std::unique_ptr<TestChromeBrowserState> chrome_browser_state_;
+  base::mac::ScopedNSAutoreleasePool pool_;
   base::scoped_nsobject<Tab> dummy_tab_;
   base::scoped_nsobject<TabModelOrderController> orderController_;
   base::scoped_nsobject<TabModel> tabModel_;
-  base::mac::ScopedNSAutoreleasePool pool_;
 };
 
 // Verifies that tabs added in the background (e.g. from context menu -> Open in
 // new tab) are inserted in the proper order.
 TEST_F(TabModelOrderControllerTest, DetermineInsertionIndexForBackgroundTabs) {
   // Add |parentTab|, then add |childTab| in the background.
   Tab* parentTab = [tabModel_ insertTabWithURL:url_
                                       referrer:referrer_
                                     windowName:nil
                                         opener:nil
@@ skipping 12 matching lines @@
   // would be inserted before the child's child.
   addTabToParentInBackground(childTab);
   index = [orderController_
       insertionIndexForTab:dummy_tab_
                 transition:ui::PAGE_TRANSITION_LINK
                     opener:parentTab
                  adjacency:TabModelOrderConstants::kAdjacentAfter];
   EXPECT_EQ(2, index);
 }
 }  // anonymous namespace