Changes

* Tracking bug: [https://bugzilla.mozilla.org/show_bug.cgi?id=975208 975208] - Specify layout of Tile Grid (resize vs more/fewer rows/columns, screen sizes, etc)

* Detailed information about the specifications: [https://bug975208.bugzilla.mozilla.org/attachment.cgi?id=8385835 implementation mock-up]

== Test Cases ==