Use EGLClientBuffer in place of HANDLE in EGL. BUG=angle:795 Change-Id: I7af47e9306e0e12b980cfd3f061bbbe0951ac4e4 Reviewed-on: https://chromium-review.googlesource.com/228913 Tested-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>