Fix base::CopyDirectory() and JumpListIcons(Old) folders' operation logic

base/files/file_util_win.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.
 
 #include "base/files/file_util.h"
 
 #include <windows.h>
 #include <io.h>
 #include <psapi.h>
 #include <shellapi.h>
@@ skipping 159 matching lines @@
     if (real_to_path.empty())
       return false;
   } else {
     real_to_path = MakeAbsoluteFilePath(real_to_path.DirName());
     if (real_to_path.empty())
       return false;
   }
   FilePath real_from_path = MakeAbsoluteFilePath(from_path);
   if (real_from_path.empty())
     return false;
+  // Originally this CopyDirectory() returns false when |to_path| string
+  // contains |from_path| string. While this can be that the to_path is within
+  // the from_path, e.g., parent-child relationship if they are both folders, it
+  // also can be that the two paths are in the same folder, just that one name
+  // contains the other, e.g. C:\\JumpListIcon and C:\\JumpListIconOld.

[gab, 2016/12/13 21:31:21]

s/JumpListIcon/Foo/ in example (since this is in //base)

also no need to escape the \ in a comment :)

[chengx, 2016/12/13 23:00:39]

Done.

+  // We make this function not return false in the latter situation by calling
+  // IsParent() function as below. This allows the copy-n-delete code after the
+  // "return false" below to execute.

[gab, 2016/12/13 21:31:21]

No need to describe history here IMO, just say:

// Note: it's important to use IsParent() here as string comparison would result
in a false positive on, e.g. C:\Foo versus C:\FooOld.

[chengx, 2016/12/13 23:00:39]

Done.

   if (real_to_path.value().size() >= real_from_path.value().size() &&
-      real_to_path.value().compare(0, real_from_path.value().size(),
-                                   real_from_path.value()) == 0) {
+      real_from_path.IsParent(real_to_path)) {
     return false;
   }
 
   int traverse_type = FileEnumerator::FILES;
   if (recursive)
     traverse_type |= FileEnumerator::DIRECTORIES;
   FileEnumerator traversal(from_path, recursive, traverse_type);
 
   if (!PathExists(from_path)) {
     DLOG(ERROR) << "CopyDirectory() couldn't stat source directory: "
@@ skipping 630 matching lines @@
     // Like Move, this function is not transactional, so we just
     // leave the copied bits behind if deleting from_path fails.
     // If to_path exists previously then we have already overwritten
     // it by now, we don't get better off by deleting the new bits.
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace base