Track original URL when downloading a redirected page

chrome/browser/android/offline_pages/background_loader_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/background_loader_offliner.h"
 
 #include "base/metrics/histogram_macros.h"
 #include "base/sys_info.h"
 #include "chrome/browser/android/offline_pages/offline_page_mhtml_archiver.h"
 #include "chrome/browser/android/offline_pages/offliner_helper.h"
@@ skipping 144 matching lines @@
       new OfflinePageMHTMLArchiver(web_contents));
 
   OfflinePageModel::SavePageParams params;
   params.url = web_contents->GetLastCommittedURL();
   params.client_id = request.client_id();
   params.proposed_offline_id = request.request_id();
   params.is_background = true;
 
   // Pass in the original URL if it's different from last committed
   // when redirects occur.
-  if (params.url != request.url())
+  if (!request.original_url().is_empty())
+    params.original_url = request.original_url();
+  else if (params.url != request.url())
     params.original_url = request.url();
 
   offline_page_model_->SavePage(
       params, std::move(archiver),
       base::Bind(&BackgroundLoaderOffliner::OnPageSaved,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 void BackgroundLoaderOffliner::RenderProcessGone(
     base::TerminationStatus status) {
@@ skipping 105 matching lines @@
       application_state ==
           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, RequestStatus::FOREGROUND_CANCELED);
   }
 }
 
 }  // namespace offline_pages