Add crash key for crashes in GLFence::Create

Also add a glFlush before calling GLFence::Create, as it should be
sufficient to trigger the crash.

Bug: 863817
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I589ba525d771895d00cf4aebfea57ce62f8add3f
Reviewed-on: https://chromium-review.googlesource.com/1148682
Commit-Queue: ccameron <ccameron@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577723}
4 files changed