- added a inspector folder,
- added related GN and gyp files,
- added task handling infrastructure for test runner.

BUG=chromium:635948
R=dgozman@chromium.org,alph@chromium.org

Committed: https://crrev.com/dc1c71c0dc8a5c4ade4aa291f2ddcd02e90c64b2
Review-Url: https://codereview.chromium.org/2361623006
Cr-Original-Commit-Position: refs/heads/master@{#39866}
Cr-Commit-Position: refs/heads/master@{#39918}