cc: Add edge case test in spiral iterator unittest.

Add edge case when tiling is smaller than tile size and center rect is
not intersecting to tiling rect. In this around index and consider
index point to the same index and as center rect is not intersecting,
it lies below the tiling rect as shown below. Double line box
represents the tile size, T represents tiling and * represents center
rect.

    ┌───┬══════╗
    │ T │      ║
    ├───┘┌───┐ ║
    ║    │ * │ ║
    ║    └───┘ ║
    ╚══════════╝

In this case, spiral iterator should return tile at (0, 0) as a valid
tile.

BUG=
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_precise_blink_rel

Review-Url: https://codereview.chromium.org/2364583002
Cr-Commit-Position: refs/heads/master@{#420824}
1 file changed