Add RetryOnFailure annotation for screenshot_sync_tests on Mac

Add RetryOnFailure to the ScreenshotSync_GPURasterWithDivs and
ScreenshotSync_SWRasterWithCanvas tests.

BUG: 978492
Change-Id: Ia378e3b7113ad2ec4ca8d2e4247c6fc6fc1a1dd4
TBR: kbr@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1676446
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Commit-Queue: Robert Kroeger <rjkroege@chromium.org>
Auto-Submit: Robert Kroeger <rjkroege@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672168}
1 file changed