Screen capture: Update record icon

This CL updates the record icon to have rounded edges, instead of
sharp/flat edges.

Precapture UI before: http://screen/7dm4n3zczZZsmCs
Precapture UI after: http://screen/3mhG4Gdjzeq4crf

"Stop recording" before: http://screen/9iWiDx9DhmYGXeD
"Stop recording" after: http://screen/5wycP9AgqTrbdwN

Notification icon before: http://screen/6a9niVtLc7KvQJZ
Notification icon after: http://screen/7CCeAXTvH2squeN

Bug: 414852990
Test: Visual
Flag: EXEMPT resource update
Change-Id: I5226674057a4191e57ffbc188b4a5ed84e1b9e9c