Add --test-page-flip-format-change to null_platform_test.

Add a flag to null_platform_test to test pageflip between
RGB and BGR.

BUG=b:29430506
TEST='null_platform_test --test-page-flip-format-change' on kevin

Change-Id: I0973defe670d6ee2c0d7d4cf64554b1f51fe88c2
Reviewed-on: https://chromium-review.googlesource.com/396358
Commit-Ready: Daniele Castagna <dcastagna@chromium.org>
Tested-by: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Zach Reizner <zachr@chromium.org>
(cherry picked from commit 8a63a60473375c442e927aec5c439bee03532591)
Reviewed-on: https://chromium-review.googlesource.com/397738
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
1 file changed