[ios] Removed canGoBack/canGoForward API from CRWSessionController.

ios/web/navigation/crw_session_controller.mm

Index: ios/web/navigation/crw_session_controller.mm
diff --git a/ios/web/navigation/crw_session_controller.mm b/ios/web/navigation/crw_session_controller.mm
index f67e7330e69f8f163a878108c81e5c26fde9284a..0dbcb0a56f2074b91b228554b5a54abe0e9dfa8f 100644
--- a/ios/web/navigation/crw_session_controller.mm
+++ b/ios/web/navigation/crw_session_controller.mm
@@ -626,14 +626,6 @@ NSString* const kWindowNameKey = @"windowName";
   DCHECK(_pendingEntryIndex == -1 || _pendingEntry);
 }
 
-- (BOOL)canGoBack {
-  return [self canGoDelta:-1];
-}
-
-- (BOOL)canGoForward {
-  return [self canGoDelta:1];
-}
-
 - (BOOL)canGoDelta:(int)delta {
   NSInteger index = [self indexOfEntryForDelta:delta];
   return 0 <= index && static_cast<NSUInteger>(index) < _entries.count;