Add EGL_ANGLE_wait_until_work_scheduled extension We're changing eglReleaseTexImage so it calls flushCommandBuffer(mtl::NoWait) instead of flushCommandBuffer(mtl::WaitUntilScheduled) and then adding an extension to allow us to WaitUntilScheduled. This is because Chrome calls eglReleaseTexImage for every canvas and having it WaitUntilScheduled per call is very slow. So instead we'll call eglWaitUntilWorkScheduledANGLE once which will effectively wait just once. Bug: angleproject:7890 Change-Id: I87bc9f9a1a7f4a0f99d93736cc3083799e76afeb Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4109311 Reviewed-by: Kenneth Russell <kbr@chromium.org> Commit-Queue: Gregg Tavares <gman@chromium.org>