Track original URL when downloading a redirected page

chrome/browser/android/offline_pages/prerendering_offliner.cc

 // Copyright 2016 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/android/offline_pages/prerendering_offliner.h"
 
 #include "base/bind.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/sys_info.h"
 #include "chrome/browser/android/offline_pages/offline_page_mhtml_archiver.h"
@@ skipping 69 matching lines @@
     std::unique_ptr<OfflinePageArchiver> archiver(
         new OfflinePageMHTMLArchiver(web_contents));
 
     OfflinePageModel::SavePageParams save_page_params;
     save_page_params.url = web_contents->GetLastCommittedURL();
     save_page_params.client_id = request.client_id();
     save_page_params.proposed_offline_id = request.request_id();
     save_page_params.is_background = true;
     // Pass in the original URL if it is different from the last committed URL
     // when redirects occur.
-    if (save_page_params.url != request.url())
+    if (!request.original_url().is_empty())
+      save_page_params.original_url = request.original_url();
+    else if (save_page_params.url != request.url())
       save_page_params.original_url = request.url();
 
     SavePage(save_page_params, std::move(archiver),
              base::Bind(&PrerenderingOffliner::OnSavePageDone,
                         weak_ptr_factory_.GetWeakPtr(), request));
   } else {
     // Clear pending request and app listener then run completion callback.
     pending_request_.reset(nullptr);
     app_listener_.reset(nullptr);
     completion_callback_.Run(request, load_status);
@@ skipping 173 matching lines @@
           base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES) {
     DVLOG(1) << "App became active, canceling current offlining request";
     SavePageRequest* request = pending_request_.get();
     Cancel();
     completion_callback_.Run(*request,
                              Offliner::RequestStatus::FOREGROUND_CANCELED);
   }
 }
 
 }  // namespace offline_pages