Login interstitial should always replace existing interstitials.

chrome/browser/ui/login/login_prompt.cc

 // Copyright (c) 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.
 
 #include "chrome/browser/ui/login/login_prompt.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 512 matching lines @@
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   WebContents* parent_contents = handler->GetWebContentsForLogin();
   if (!parent_contents || handler->WasAuthHandled()) {
     // The request may have been cancelled, or it may be for a renderer
     // not hosted by a tab (e.g. an extension). Cancel just in case
     // (cancelling twice is a no-op).
     handler->CancelAuth();
     return;
   }
 
-  // Check if the request is cross origin. There are two different ways the
-  // navigation can occur:
+  // Check if this is a main frame navigation and
+  // (a) if the request is cross origin or
+  // (b) if an interstitial is already being shown.
+  //
+  // For (a), there are two different ways the navigation can occur:
   // 1- The user enters the resource URL in the omnibox.
   // 2- The page redirects to the resource.
   // In both cases, the last committed URL is different than the resource URL,
   // so checking it is sufficient.
   // Note that (1) will not be true once site isolation is enabled, as any
   // navigation could cause a cross-process swap, including link clicks.
-  if (is_main_frame &&
-      parent_contents->GetLastCommittedURL().GetOrigin() !=
-          request_url.GetOrigin()) {
+  //
+  // For (b), the login interstitial should always replace an existing
+  // interstitial. This is because |LoginHandler::CloseContentsDeferred| tries
+  // to proceed whatever interstitial is being shown when the login dialog is
+  // closed, so that interstitial should only be a login interstitial.
+  if (is_main_frame && (parent_contents->ShowingInterstitialPage() ||
+                        parent_contents->GetLastCommittedURL().GetOrigin() !=
+                            request_url.GetOrigin())) {
     // Show a blank interstitial for main-frame, cross origin requests
     // so that the correct URL is shown in the omnibox.
     base::Closure callback = base::Bind(&ShowLoginPrompt,
                                         request_url,
                                         make_scoped_refptr(auth_info),
                                         make_scoped_refptr(handler));
-    // This is owned by the interstitial it creates.
+    // This is owned by the interstitial it creates. It cancels any existing
+    // interstitial.
     new LoginInterstitialDelegate(parent_contents,
                                   request_url,
                                   callback);
   } else {
     ShowLoginPrompt(request_url,
                     auth_info,
                     handler);
   }
 }
 
 // ----------------------------------------------------------------------------
 // Public API
 
 LoginHandler* CreateLoginPrompt(net::AuthChallengeInfo* auth_info,
                                 net::URLRequest* request) {
   bool is_main_frame = (request->load_flags() & net::LOAD_MAIN_FRAME) != 0;
   LoginHandler* handler = LoginHandler::Create(auth_info, request);
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&LoginDialogCallback, request->url(),
                  make_scoped_refptr(auth_info), make_scoped_refptr(handler),
                  is_main_frame));
   return handler;
 }