Auto grid lines, lower minimum, disable estimates.

Show automatic grid lines with power-of-two spacing, avoiding ANR
when trying to render thousands of gridlines.  Lower minimum chart
height to 50MB to give better view of linear data.  Also disable
estimates rendering.

Bug: 5500204, 6005240
Change-Id: Iacfed11b32c0095c9c2d08bee6a1b5e29637de98