And some refactoring to the existing code for LiveEdit.

R=jarin@chromium.org

Change-Id: Ic1d626db9722b39cbcd83bf6878fc24d6094e612
Reviewed-on: https://chromium-review.googlesource.com/687014
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48233}