Use previous target path when resuming a download after crash

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 609 matching lines @@
 const base::FilePath& DownloadItemImpl::GetTargetFilePath() const {
   return target_path_;
 }
 
 const base::FilePath& DownloadItemImpl::GetForcedFilePath() const {
   // TODO(asanka): Get rid of GetForcedFilePath(). We should instead just
   // require that clients respect GetTargetFilePath() if it is already set.
   return forced_file_path_;
 }
 
+base::FilePath DownloadItemImpl::GetLastUsedTargetPath() const {

[asanka, 2017/01/10 19:34:19]

Is there a case where GetTargetFilePath() and GetForcedFilePath() differ?

The only one I can think of is where the download gets destroyed or the devices
crashes during the initial download target determination. IMHO, if things go
south that close to the download initiation, it's much safer to discard the
intermediate file and start from the beginning. Before the first download target
determination, it's not accurate to refer to the value of GetForcedFilePath() as
the last used target path.

Let's get rid of this method if there is no other use case for it.

[qinmin, 2017/01/10 22:06:29]

Done.

+  if (GetForcedFilePath().empty())
+    return GetTargetFilePath();
+  return GetForcedFilePath();
+}
+
 base::FilePath DownloadItemImpl::GetFileNameToReportUser() const {
   if (!display_name_.empty())
     return display_name_;
   return target_path_.BaseName();
 }
 
 DownloadItem::TargetDisposition DownloadItemImpl::GetTargetDisposition() const {
   return target_disposition_;
 }
 
@@ skipping 1476 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