infobars: Remove the downcast AsAlternateNavInfoBarDelegate() function.

chrome/browser/ui/cocoa/infobars/alternate_nav_infobar_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 "chrome/browser/ui/cocoa/infobars/alternate_nav_infobar_controller.h"
 
 #include "base/logging.h"
 #include "base/sys_string_conversions.h"
 #import "chrome/browser/ui/cocoa/hyperlink_text_view.h"
 #include "chrome/browser/ui/cocoa/event_utils.h"
 #include "chrome/browser/ui/cocoa/infobars/infobar.h"
 #include "chrome/browser/ui/omnibox/alternate_nav_infobar_delegate.h"
 #include "webkit/glue/window_open_disposition.h"
 
 @implementation AlternateNavInfoBarController
 
 // Link infobars have a text message, of which part is linkified.  We
 // use an NSAttributedString to display styled text, and we set a
 // NSLink attribute on the hyperlink portion of the message.  Infobars
 // use a custom NSTextField subclass, which allows us to override
 // textView:clickedOnLink:atIndex: and intercept clicks.
 //
 - (void)addAdditionalControls {
   // No buttons.
   [self removeButtons];
 
   AlternateNavInfoBarDelegate* delegate =
-      delegate_->AsAlternateNavInfoBarDelegate();
+      static_cast<AlternateNavInfoBarDelegate*>(delegate_);
   DCHECK(delegate);
   size_t offset = string16::npos;
   string16 message = delegate->GetMessageTextWithOffset(&offset);
   string16 link = delegate->GetLinkText();
   NSFont* font = [NSFont labelFontOfSize:
                   [NSFont systemFontSizeForControlSize:NSRegularControlSize]];
   HyperlinkTextView* view = (HyperlinkTextView*)label_.get();
   [view setMessageAndLink:base::SysUTF16ToNSString(message)
                  withLink:base::SysUTF16ToNSString(link)
                  atOffset:offset
                      font:font
              messageColor:[NSColor blackColor]
                 linkColor:[NSColor blueColor]];
 }
 
 // Called when someone clicks on the link in the infobar.  This method
 // is called by the InfobarTextField on its delegate (the
 // AlternateNavInfoBarController).
 - (void)linkClicked {
   if (![self isOwned])
     return;
   WindowOpenDisposition disposition =
       event_utils::WindowOpenDispositionFromNSEvent([NSApp currentEvent]);
-  if (delegate_->AsAlternateNavInfoBarDelegate()->LinkClicked(disposition))
+  AlternateNavInfoBarDelegate* delegate =
+      static_cast<AlternateNavInfoBarDelegate*>(delegate_);
+  if (delegate->LinkClicked(disposition))
     [self removeSelf];
 }
 
 @end
 
 InfoBar* AlternateNavInfoBarDelegate::CreateInfoBar(InfoBarService* owner) {
   AlternateNavInfoBarController* controller =
       [[AlternateNavInfoBarController alloc] initWithDelegate:this owner:owner];
   return new InfoBar(controller, this);
 }