Report more relevant error code for windows base::ReplaceFile impl

base/files/file_util_win.cc

Index: base/files/file_util_win.cc
diff --git a/base/files/file_util_win.cc b/base/files/file_util_win.cc
index 4e67b5a348653f3af41d897f845ce4e0df4f2571..9cb446bc87ce581cdb7088551c72ec0d134d2334 100644
--- a/base/files/file_util_win.cc
+++ b/base/files/file_util_win.cc
@@ -134,6 +134,8 @@ bool ReplaceFile(const FilePath& from_path,
   // already exist.
   if (::MoveFile(from_path.value().c_str(), to_path.value().c_str()))
     return true;
+  File::Error move_error = File::OSErrorToFileError(GetLastError());

[dcheng, 2017/02/07 23:24:50]

DWORD error_code = ::GetLastError();

+
   // Try the full-blown replace if the move fails, as ReplaceFile will only
   // succeed when |to_path| does exist. When writing to a network share, we may
   // not be able to change the ACLs. Ignore ACL errors then
@@ -142,8 +144,14 @@ bool ReplaceFile(const FilePath& from_path,
                     REPLACEFILE_IGNORE_MERGE_ERRORS, NULL, NULL)) {
     return true;
   }
-  if (error)
-    *error = File::OSErrorToFileError(GetLastError());
+  // In the case of FILE_ERROR_NOT_FOUND from ReplaceFile, it is likely that
+  // |to_path| does not exist. In this case, the more relevant error comes
+  // from the call to MoveFile.
+  if (error) {
+    File::Error replace_error = File::OSErrorToFileError(GetLastError());
+    *error = replace_error == File::FILE_ERROR_NOT_FOUND ? move_error

[dcheng, 2017/02/07 23:24:50]

if ((replace_error = ::GetLastError()) != ERROR_FILE_NOT_FOUND)
  error_code = replace_error;
if (error)
  *error = File::OSErrorToFileError(error_code);

[Charlie Harrison, 2017/02/07 23:31:23]

Going to push back on this, only because I think if we're comparing the raw
error we'll have to check PATH_NOT_FOUND as well. OSErrorToFileError combines
them into a single NOT_FOUND.

[dcheng, 2017/02/07 23:32:39]

Makes sense, I'm OK with that.

+                                                         : replace_error;
+  }
   return false;
 }