swapChainDesc.SwapEffect wasn't being set. The whole structure was initialized
to 0 and DXGI_SWAP_EFFECT_DISCARD has value 0 so this should have no effect.
Also sorted the field initialization in the order they're declared.

BUG=373360

Change-Id: If0113e7468c0bad024a07fec6ad9e223e19494b5
Reviewed-on: https://chromium-review.googlesource.com/200046Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Nicolas Capens <nicolascapens@chromium.org>