Do not suppress HTTP Authenticaiton in WebController.

ios/chrome/browser/tabs/tab.h

 // 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.
 
 #ifndef IOS_CHROME_BROWSER_TABS_TAB_H_
 #define IOS_CHROME_BROWSER_TABS_TAB_H_
 
 #import <UIKit/UIKit.h>
 
 #include <memory>
@@ skipping 331 matching lines @@
 
 // Called when this tab is shown.
 - (void)wasShown;
 
 // Called when this tab is hidden.
 - (void)wasHidden;
 
 // Evaluates U2F result.
 - (void)evaluateU2FResultFromURL:(const GURL&)url;
 
+// Cancels prerendering. Can be called only for prerender tabs (where

[marq (ping after 24h), 2017/03/27 13:00:13]

Can you clarify how the 'can only be called for prerender tabs' contract is
enforced?

[Eugene But (OOO till 7-30), 2017/03/27 16:46:50]

It is enforced via DCHECK like in other invariant in Chrome code. Is this
something that you want me to document in the comments? For me this seems pretty
standard way to enforce the contracts.

[marq (ping after 24h), 2017/03/27 17:04:30]

I was mostly looking for a clearer statement in the comment -- "It is an error
to call this on anything except a prerender tab" as opposed to (say) "Calling
this on a non-prerender tab does nothing".

[Eugene But (OOO till 7-30), 2017/03/27 17:19:07]

Thanks for clarification. Done.

+// |isPrerenderTab| is set to YES).
+- (void)discardPrerender;
+
 @end
 
 #endif  // IOS_CHROME_BROWSER_TABS_TAB_H_