Increasing Header height to 72dp.

As per UX spec, the header height needs to
be 72 dp, with the settings gear, unlock button
in middle occupying 48dp, leaving 12dp padding
above and below the latter in header.

Before: https://photos.app.goo.gl/j4vtTQXWy93DRwGA6
After: https://photos.app.goo.gl/7SxLdCQh7KJzYYLx5

Fix: 336510036
Test: Verified on device.
Flag: NA
Change-Id: I7c8115bf3c9b5832a2abcc4a710a2ccf78784c2b