lgtm https://codereview.appspot.com/6827053/diff/1/tests/TileGridTest.cpp File tests/TileGridTest.cpp (right): https://codereview.appspot.com/6827053/diff/1/tests/TileGridTest.cpp#newcode29 tests/TileGridTest.cpp:29: REPORTER_ASSERT(reporter, grid.tile(1,1).count() == ((tileMask & kBottomRight_Tile)? 1 : 0)); 100 columns.