Add testing for GridMigration.

Bug: 325286145
Flag: ACONFIG grid_migration_fix disabled
Test: GridMigrationTest
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:851b1f3b1c103b28d6df6653693ee132c92086e7)
Merged-In: I49fd32be895f3a05204775373b9eec62d9026f3b
Change-Id: I49fd32be895f3a05204775373b9eec62d9026f3b
9 files changed