[ios] Removed back-forward navigation API from CRWWebController.

ios/web/web_state/ui/crw_web_controller.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/web_state/ui/crw_web_controller.h"
 
 #import <WebKit/WebKit.h>
 
 #import <objc/runtime.h>
 #include <stddef.h>
@@ skipping 1361 matching lines @@
 
     UIImage* result = UIGraphicsGetImageFromCurrentImageContext();
     UIGraphicsEndImageContext();
 
     defaultImage =
         [[result stretchableImageWithLeftCapWidth:1 topCapHeight:1] retain];
   }
   return defaultImage;
 }
 
-- (BOOL)canGoBack {
-  return _webStateImpl->GetNavigationManagerImpl().CanGoBack();
-}
-
-- (BOOL)canGoForward {
-  return _webStateImpl->GetNavigationManagerImpl().CanGoForward();
-}
-
 - (CGPoint)scrollPosition {
   CGPoint position = CGPointMake(0.0, 0.0);
   if (!self.webScrollView)
     return position;
   return self.webScrollView.contentOffset;
 }
 
 - (BOOL)atTop {
   if (!_webView)
     return YES;
@@ skipping 874 matching lines @@
             _URLOnStartLoading, false);
         _webStateImpl->SetIsLoading(false);
       }
       [_delegate webLoadCancelled:_URLOnStartLoading];
       break;
     case web::PAGE_LOADED:
       break;
   }
 }
 
-- (void)goBack {
-  [self goDelta:-1];
-}
-
-- (void)goForward {
-  [self goDelta:1];
-}
-
 - (void)goDelta:(int)delta {
   if (delta == 0) {
     [self reload];
   } else if ([self.sessionController canGoDelta:delta]) {
     [self goToItemAtIndex:[self.sessionController indexOfEntryForDelta:delta]];
   }
 }
 
 - (void)goToItemAtIndex:(int)index {
   NSArray* entries = self.sessionController.entries;
@@ skipping 723 matching lines @@
     item->SetIsCreatedFromHashChange(true);
   }
 
   // Notify the observers.
   _webStateImpl->OnUrlHashChanged();
   return YES;
 }
 
 - (BOOL)handleWindowHistoryBackMessage:(base::DictionaryValue*)message
                                context:(NSDictionary*)context {
-  [self goBack];
+  [self goDelta:-1];
   return YES;
 }
 
 - (BOOL)handleWindowHistoryForwardMessage:(base::DictionaryValue*)message
                                   context:(NSDictionary*)context {
-  [self goForward];
+  [self goDelta:1];
   return YES;
 }
 
 - (BOOL)handleWindowHistoryGoMessage:(base::DictionaryValue*)message
                              context:(NSDictionary*)context {
   int delta;
   message->GetInteger("value", &delta);
   [self goDelta:delta];
   return YES;
 }
@@ skipping 2687 matching lines @@
   }
 
   return web::WEB_VIEW_DOCUMENT_TYPE_GENERIC;
 }
 
 - (NSString*)refererFromNavigationAction:(WKNavigationAction*)action {
   return [action.request valueForHTTPHeaderField:@"Referer"];
 }
 
 @end