Cleanup: Initialize Value from tools/gn by moving std::string

Previously it used string::swap, but std::move is more effective in this case.

BUG=367418
TEST=
R=brettw@chromium.org

Review-Url: https://codereview.chromium.org/1350043004
Cr-Original-Commit-Position: refs/heads/master@{#399012}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 0b310e43469a5ef54d76661ec36e4a7e1ca09d3f
1 file changed
tree: 1488e7129487ea06577237d474c8d5fc974f3a61
  1. tools/