[iOS][MF] Fixes the size of the popover for passwords

Reduces the estimated size of the row to the minimum, so it is correctly
calculated on |contentSize|.
Starts the view controller with a more appropiate size for the popover.

Bug: 912515
Change-Id: If7c2dc4a0ab2a6df445fdac2c5fc21453927a71c
Reviewed-on: https://chromium-review.googlesource.com/c/1371873
Commit-Queue: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615855}
2 files changed