add DCHECK that a server redirect pending item should never be added.

ios/chrome/browser/web/navigation_manager_util_unittest.mm

 // Copyright 2017 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/web/navigation_manager_util.h"
 
 #import "ios/web/public/navigation_item.h"
 #import "ios/web/public/test/fakes/test_navigation_manager.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #import "testing/gtest_mac.h"
@@ skipping 39 matching lines @@
                        ui::PAGE_TRANSITION_CLIENT_REDIRECT);
   web::NavigationItem* item = GetLastNonRedirectedItem(&nav_manager_);
   ASSERT_TRUE(item);
   EXPECT_TRUE(ui::PageTransitionTypeIncludingQualifiersIs(
       item->GetTransitionType(), ui::PAGE_TRANSITION_LINK));
 }
 
 // Tests that when all items are redirects, the first one is returned.
 TEST_F(NavigationManagerUtilTest, TestLastNonRedirectedItemAllRedirects) {
   nav_manager_.AddItem(GURL("http://bar.com/redir0"),
-                       ui::PAGE_TRANSITION_SERVER_REDIRECT);
+                       ui::PAGE_TRANSITION_CLIENT_REDIRECT);
   nav_manager_.AddItem(GURL("http://bar.com/redir1"),
                        ui::PAGE_TRANSITION_CLIENT_REDIRECT);
   nav_manager_.AddItem(GURL("http://bar.com/redir2"),
                        ui::PAGE_TRANSITION_CLIENT_REDIRECT);
   web::NavigationItem* item = GetLastNonRedirectedItem(&nav_manager_);
   ASSERT_TRUE(item);
-  EXPECT_TRUE(ui::PageTransitionTypeIncludingQualifiersIs(
-      item->GetTransitionType(), ui::PAGE_TRANSITION_SERVER_REDIRECT));
+  EXPECT_EQ(GURL("http://bar.com/redir0"), item->GetURL());
 }
 
 // Tests that earlier redirects are not found.
 TEST_F(NavigationManagerUtilTest, TestLastNonRedirectedItemNotEarliest) {
   nav_manager_.AddItem(GURL("http://foo.com/bookmark"),
                        ui::PAGE_TRANSITION_AUTO_BOOKMARK);
   nav_manager_.AddItem(GURL("http://foo.com/page0"), ui::PAGE_TRANSITION_TYPED);
   nav_manager_.AddItem(GURL("http://bar.com/redir1"),
                        ui::PAGE_TRANSITION_CLIENT_REDIRECT);
   nav_manager_.AddItem(GURL("http://bar.com/redir2"),
                        ui::PAGE_TRANSITION_CLIENT_REDIRECT);
   web::NavigationItem* item = GetLastNonRedirectedItem(&nav_manager_);
   ASSERT_TRUE(item);
   EXPECT_TRUE(ui::PageTransitionTypeIncludingQualifiersIs(
       item->GetTransitionType(), ui::PAGE_TRANSITION_TYPED));
 }