Login screen redesign (CL 2)

Make the lock screen PIN keyboard look the same with the mock here:
https://gallery.googleplex.com/projects/MCHbtQVoQ2HCZdwfnbqy2eSi/files/MCEk7MHTx6J1ur9AuP2SqZvcwMSJbxAVNpw

It does not change the underlying implementation of PIN keyboard at all.

BUG=718174
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2881243002
Cr-Commit-Position: refs/heads/master@{#473110}
6 files changed