ChromeOS: GAIA screen should support API v2.

This CL adds support for GAIA V2 API.

BUG=709244
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2947263002
Cr-Commit-Position: refs/heads/master@{#481493}
3 files changed