This test creates a predictable 256x256 pattern in an FBO (i.e. x-axis
is red and y-axis is green), and then uses glBlitFramebuffer() to blit
all or different halves of that FBO to the default framebuffer
(i.e. the Vulkan swapchain).  When run on a rotated Android device,
the predictable pattern helps to determine if/how anything is wrong.

Bug: b/158337857
Change-Id: I858964fcb34b8ee5fbdbeade0e1dacaafaea7fa3
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2236994Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Ian Elliott <ianelliott@google.com>
Commit-Queue: Ian Elliott <ianelliott@google.com>