tools/gn: replace usage of linked_ptr by using scoped_ptr

With C++11, we can use scoped_ptr in STL containers now.

BUG=556939
TEST=gn gen + gn_unittests
R=brettw@chromium.org

Review URL: https://codereview.chromium.org/1480423003

Cr-Original-Commit-Position: refs/heads/master@{#362520}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 4695e89361e0fdc2eaa3b3ba57362fa6e05f10cf
1 file changed
tree: a929045eb07137b5b3e607e1ecc157efe1999f86
  1. tools/