[Downloads] Update origin info after each response.

content/browser/download/download_item_impl.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.
 
 // File method ordering: Methods in this file are in the same order as
 // in download_item_impl.h, with the following exception: The public
 // interface Start is placed in chronological order with the other
 // (private) routines that together define a DownloadItem's state
 // transitions as the download progresses.  See "Download progression
 // cascade" later in this file.
@@ skipping 878 matching lines @@
     case DOWNLOAD_INTERRUPT_REASON_USER_CANCELED:
     case DOWNLOAD_INTERRUPT_REASON_FILE_BLOCKED:
     case DOWNLOAD_INTERRUPT_REASON_FILE_SECURITY_CHECK_FAILED:
       mode = RESUME_MODE_INVALID;
       break;
   }
 
   return mode;
 }
 
+void DownloadItemImpl::MergeOriginInfoOnResume(
+    const DownloadCreateInfo& new_create_info) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK_EQ(RESUMING_INTERNAL, state_);
+  DCHECK(!new_create_info.url_chain.empty());
+
+  // We are going to tack on any new redirects to our list of redirects.
+  // When a download is resumed, the URL used for the resumption request is the
+  // one at the end of the previous redirect chain. Tacking additional redirects
+  // to the end of this chain ensures that:
+  // - If the download needs to be resumed again, the ETag/Last-Modified headers
+  //   will be used with the last server that sent them to us.
+  // - The redirect chain contains all the servers that were involved in this
+  //   download since the initial request, in order.
+  std::vector<GURL>::const_iterator chain_iter =
+      new_create_info.url_chain.begin();
+  if (*chain_iter == url_chain_.back())
+    ++chain_iter;
+
+  // Record some stats. If the precondition failed (the server returned
+  // HTTP_PRECONDITION_FAILED), then the download will automatically retried as
+  // a full request rather than a partial. Full restarts clobber validators.
+  int origin_state = 0;
+  if (chain_iter != new_create_info.url_chain.end())
+    origin_state |= ORIGIN_STATE_ON_RESUMPTION_ADDITIONAL_REDIRECTS;
+  if (etag_ != new_create_info.etag ||
+      last_modified_time_ != new_create_info.last_modified)
+    origin_state |= ORIGIN_STATE_ON_RESUMPTION_VALIDATORS_CHANGED;
+  if (content_disposition_ != new_create_info.content_disposition)
+    origin_state |= ORIGIN_STATE_ON_RESUMPTION_CONTENT_DISPOSITION_CHANGED;
+  RecordOriginStateOnResumption(new_create_info.save_info->offset != 0,
+                                origin_state);
+
+  url_chain_.insert(
+      url_chain_.end(), chain_iter, new_create_info.url_chain.end());
+  etag_ = new_create_info.etag;
+  last_modified_time_ = new_create_info.last_modified;
+  content_disposition_ = new_create_info.content_disposition;
+
+  // Don't update observers. This method is expected to be called just before a
+  // DownloadFile is created and Start() is called. The observers will be
+  // notified when the download transitions to the IN_PROGRESS state.
+}
+
 void DownloadItemImpl::NotifyRemoved() {
   FOR_EACH_OBSERVER(Observer, observers_, OnDownloadRemoved(this));
 }
 
 void DownloadItemImpl::OnDownloadedFileRemoved() {
   file_externally_removed_ = true;
   VLOG(20) << __FUNCTION__ << " download=" << DebugString(true);
   UpdateObservers();
 }
 
@@ skipping 795 matching lines @@
     case RESUME_MODE_USER_CONTINUE:
       return "USER_CONTINUE";
     case RESUME_MODE_USER_RESTART:
       return "USER_RESTART";
   }
   NOTREACHED() << "Unknown resume mode " << mode;
   return "unknown";
 }
 
 }  // namespace content