Fix problems with cross-origin redirects.

Source/core/loader/DocumentThreadableLoader.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 169 matching lines @@
 
     RefPtr<DocumentThreadableLoader> protect(this);
     // Allow same origin requests to continue after allowing clients to audit the redirect.
     if (isAllowedRedirect(request.url())) {
         if (m_client->isDocumentThreadableLoaderClient())
             static_cast<DocumentThreadableLoaderClient*>(m_client)->willSendRequest(request, redirectResponse);
         return;
     }
 
     // When using access control, only simple cross origin requests are allowed to redirect. The new request URL must have a supported
-    // scheme and not contain the userinfo production. In addition, the redirect response must pass the access control check.
+    // scheme and not contain the userinfo production. In addition, the redirect response must pass the access control check if the
+    // original request was not same-origin.
     if (m_options.crossOriginRequestPolicy == UseAccessControl) {
         bool allowRedirect = false;
         if (m_simpleRequest) {
             String accessControlErrorDescription;
             allowRedirect = SchemeRegistry::shouldTreatURLSchemeAsCORSEnabled(request.url().protocol())
                             && request.url().user().isEmpty()
                             && request.url().pass().isEmpty()
-                            && passesAccessControlCheck(redirectResponse, m_options.allowCredentials, securityOrigin(), accessControlErrorDescription);
+                            && (m_sameOriginRequest || passesAccessControlCheck(redirectResponse, m_options.allowCredentials, securityOrigin(), accessControlErrorDescription));
         }
 
         if (allowRedirect) {
             if (m_resource)
                 clearResource();
 
             RefPtr<SecurityOrigin> originalOrigin = SecurityOrigin::createFromString(redirectResponse.url());
             RefPtr<SecurityOrigin> requestOrigin = SecurityOrigin::createFromString(request.url());
-            // If the request URL origin is not same origin with the original URL origin, set source origin to a globally unique identifier.
-            if (!originalOrigin->isSameSchemeHostPort(requestOrigin.get()))
+            // If the original request wasn't same-origin, then if the request URL origin is not same origin with the original URL origin,
+            // set the source origin to a globally unique identifier. (If the original request was same-origin, the origin of the new request
+            // should be the original URL origin.)
+            if (!m_sameOriginRequest && !originalOrigin->isSameSchemeHostPort(requestOrigin.get()))
                 m_options.securityOrigin = SecurityOrigin::createUnique();
             // Force any subsequent requests to use these checks.
             m_sameOriginRequest = false;
 
+            // Since the request is no longer same-origin, if the user didn't request credentials in
+            // the first place, update our state so we neither request them nor expect they must be allowed.
+            if (m_options.credentialsRequested == ClientDidNotRequestCredentials)
+                m_options.allowCredentials = DoNotAllowStoredCredentials;
+
             // Remove any headers that may have been added by the network layer that cause access control to fail.
             request.clearHTTPContentType();
             request.clearHTTPReferrer();
             request.clearHTTPOrigin();
             request.clearHTTPUserAgent();
             request.clearHTTPAccept();
             makeCrossOriginAccessRequest(request);
             return;
         }
     }
@@ skipping 211 matching lines @@
 
     return m_sameOriginRequest && securityOrigin()->canRequest(url);
 }
 
 SecurityOrigin* DocumentThreadableLoader::securityOrigin() const
 {
     return m_options.securityOrigin ? m_options.securityOrigin.get() : m_document->securityOrigin();
 }
 
 } // namespace WebCore