Add EGL spec for EGL_ANGLE_direct_composition This allows applications to specify that they want to render to the screen using DirectComposition. This can save power by allowing the use of DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL and DirectFlip, but has other side effects - windows must be owned by the current process, and contents drawn by GDI are shown underneatch the window. BUG=angleproject:1178 Change-Id: I2e45d92c9f92f27eedaf50f0a866c20c43f3aab5 Reviewed-on: https://chromium-review.googlesource.com/317651 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Tested-by: John Bauman <jbauman@chromium.org>