Adds NavigationManager util functions to ios/chrome/browser/web/

ios/chrome/browser/web/navigation_manager_util.h

Index: ios/chrome/browser/web/navigation_manager_util.h
diff --git a/ios/chrome/browser/web/navigation_manager_util.h b/ios/chrome/browser/web/navigation_manager_util.h
new file mode 100644
index 0000000000000000000000000000000000000000..24ec5b38c296fe3380892ad4dfbabae689f2d16e
--- /dev/null
+++ b/ios/chrome/browser/web/navigation_manager_util.h
@@ -0,0 +1,19 @@
+// 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.
+
+#ifndef IOS_CHROME_BROWSER_WEB_NAVIGATION_MANAGER_UTIL_H_
+#define IOS_CHROME_BROWSER_WEB_NAVIGATION_MANAGER_UTIL_H_
+
+#import "ios/web/public/navigation_item.h"
+#import "ios/web/public/navigation_manager.h"
+
+// Utility functions built on web::NavigationManager public API.
+
+// Returns the most recent navigation item that is not the result of an HTTP
+// Redirect. Returns nullptr if |nav_manager| is empty or the first item if

[Eugene But (OOO till 7-30), 2017/03/17 14:32:04]

It's quite unexpected that GetLastNonRedirectedItem can actually return a
redirect item. Is there a reason for that?

[kkhorimoto, 2017/03/17 17:16:58]

The only use case of |-lastUserItem| was for reloading a page using a new user
agent, so if we traverse the whole history and the last one is a REDIRECT type,
we still return it because that's the best idea we have for the URL to attempt
to reload.  You're right that this is unexpected behavior given the new naming. 
Maybe we should just return nullptr in that case, then handle a null return
value when we're actually doing the reload.

[pkl (ping after 24h if needed), 2017/03/17 20:23:52]

Acknowledged.

[pkl (ping after 24h if needed), 2017/03/17 20:23:53]

I'm inclined to preserve the existing behavior and then clean up separately.

+// all items are redirects.
+web::NavigationItem* GetLastNonRedirectedItem(
+    web::NavigationManager* nav_manager);
+
+#endif  // IOS_CHROME_BROWSER_WEB_NAVIGATION_MANAGER_UTIL_H_