Fix an issue that download may missing MIME type if it failed ealier

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 977 matching lines @@
     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(received_bytes_ != 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;
+  // It is possible that the previous download attempt failed right before the
+  // response is received. Need to reset the MIME type.
+  mime_type_ = new_create_info.mime_type;
 
   // 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 (auto& observer : observers_)
     observer.OnDownloadRemoved(this);
 }
@@ skipping 1109 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