VR: Add a Linux-based VR UI testapp

This app draws the VR UI in a window on Linux, using fake browser
state.  This lets us debug UI appearance and implementation without
building and loading the full Android APK.

BUG=769325

Change-Id: I1a0efd7376d5103ed98641587f559ba8a5f65450
Reviewed-on: https://chromium-review.googlesource.com/682754
Commit-Queue: Christopher Grant <[email protected]>
Reviewed-by: Tibor Goldschwendt <[email protected]>
Reviewed-by: Michael Spang <[email protected]>
Reviewed-by: Andrew Grieve <[email protected]>
Cr-Commit-Position: refs/heads/master@{#505254}
diff --git a/BUILD.gn b/BUILD.gn
index eae5821..1200abe 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -720,7 +720,9 @@
 
   if (enable_vr) {
     deps += [ "//chrome/browser/vr:vr_common_unittests" ]
-
+    if (is_linux && use_ozone) {
+      deps += [ "//chrome/browser/vr/testapp:vr_testapp" ]
+    }
     if (is_android) {
       deps += [ "//tools/perf/contrib/vr_benchmarks:vr_perf_tests" ]
     }