GitLab

* Polymer framework was used in the implementation
* Created custom element <oobe-screen>.
* HostPairingScreen was converted to <host-paring-screen> which extends <oobe-screen>.
* Several <core-*> Polymer elements were used.
* Roboto font used.

Polymer elements and fonts are imported to the page in a runtime, in contrast with a current implementation, where almost all resources are unlined. Can't say how runtime imports affect a performance.

BUG=375191
TEST=manually

Review URL: https://codereview.chromium.org/599273004

Cr-Commit-Position: refs/heads/master@{#297244}