VR: handle content quad drawing in Ui

Also renaming WebVrRenderer to TextureCopyRenderer, given that it is not
only being used for rendering WebXR.

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:linux_vr;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: Ib6ba330bde972b4d87b8e4b897957f5f37bb7364
Reviewed-on: https://chromium-review.googlesource.com/1168469
Reviewed-by: Michael Thiessen <mthiesse@chromium.org>
Commit-Queue: Aldo Culquicondor <acondor@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582762}
11 files changed