[ios] Removed goBack/goForward from CRWSessionController.

ios/web/navigation/crw_session_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.
 
 #import "ios/web/navigation/crw_session_controller.h"
 
 #import <Foundation/Foundation.h>
 
 #include <utility>
 
@@ skipping 567 matching lines @@
 
 // Tests state of an empty session controller.
 TEST_F(CRWSessionControllerTest, EmptyController) {
   EXPECT_EQ(0U, [[session_controller_ entries] count]);
   EXPECT_EQ(-1, [session_controller_ currentNavigationIndex]);
   EXPECT_EQ(-1, [session_controller_ previousNavigationIndex]);
   EXPECT_FALSE([session_controller_ currentEntry]);
   EXPECT_FALSE([session_controller_ pendingEntry]);
   EXPECT_EQ(-1, [session_controller_ pendingEntryIndex]);
   EXPECT_EQ(-1, [session_controller_ indexOfEntryForDelta:0]);
+  EXPECT_EQ(nil, [session_controller_ currentEntry]);
 }
 
 // Tests going delta, including out of range cases.
 TEST_F(CRWSessionControllerTest, GoDelta) {
   [session_controller_ addPendingEntry:GURL("http://www.example.com/0")
                               referrer:MakeReferrer("http://www.example.com/a")
                             transition:ui::PAGE_TRANSITION_LINK
                      rendererInitiated:NO];
   [session_controller_ commitPendingEntry];
   [session_controller_ addPendingEntry:GURL("http://www.example.com/redirect")
@@ skipping 619 matching lines @@
 
   [session_controller_ setPendingEntryIndex:0];
 
   web::NavigationItem* visible_item =
       [[session_controller_ visibleEntry] navigationItem];
   ASSERT_TRUE(visible_item);
   EXPECT_EQ("http://www.example.com/0", visible_item->GetURL().spec());
 }
 
 }  // anonymous namespace