Web shell test to go back and forward.

ios/web/shell/view_controller.mm

 // Copyright 2014 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/shell/view_controller.h"
 
 #include <stdint.h>
 
 #include <memory>
 #include <utility>
@@ skipping 45 matching lines @@
   }
   return self;
 }
 
 - (void)dealloc {
   net::HTTPProtocolHandlerDelegate::SetInstance(nullptr);
   net::RequestTracker::SetRequestTrackerFactory(nullptr);
   [super dealloc];
 }
 
+- (CRWWebController*)webController {
+  return _webController;
+}
+
 - (void)viewDidLoad {
   [super viewDidLoad];
 
   // Set up the toolbar buttons.
   UIButton* back = [UIButton buttonWithType:UIButtonTypeCustom];
   [back setImage:[UIImage imageNamed:@"toolbar_back"]
         forState:UIControlStateNormal];
   [back setFrame:CGRectMake(0, 0, 44, 44)];
   [back setImageEdgeInsets:UIEdgeInsetsMake(5, 5, 4, 4)];
   [back setAutoresizingMask:UIViewAutoresizingFlexibleRightMargin];
@@ skipping 272 matching lines @@
 - (void)webWillFinishHistoryNavigationFromEntry:(CRWSessionEntry*)fromEntry {
 }
 - (int)downloadImageAtUrl:(const GURL&)url
             maxBitmapSize:(uint32_t)maxBitmapSize
                  callback:
                      (const web::WebState::ImageDownloadCallback&)callback {
   return -1;
 }
 
 @end