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This change adds the plumbing necessary to create a UI using a future native
feature module library.  The code is currently behind a define, which will
become a feature flag.

Bug=

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: I8f71a78f980bda790517d0bd7c41ed091ce66c52
Reviewed-on: https://chromium-review.googlesource.com/1181924Reviewed-by: Aldo Culquicondor <acondor@chromium.org>
Reviewed-by: Ian Vollick <vollick@chromium.org>
Commit-Queue: Christopher Grant <cjgrant@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584751}