Implement a means of letting native VR Shell control the HTML UI.

chrome/browser/android/vr_shell/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/rules.gni")
 import("//chrome/common/features.gni")
 import("//testing/test.gni")
 
 assert(enable_vr_shell || enable_webvr)
 
 static_library("vr_common") {
   sources = [
     "animation.cc",
     "animation.h",
     "easing.cc",
     "easing.h",
     "ui_elements.cc",
     "ui_elements.h",
+    "ui_interface.cc",
+    "ui_interface.h",
     "ui_scene.cc",
     "ui_scene.h",
     "vr_compositor.cc",
     "vr_compositor.h",
     "vr_controller.cc",
     "vr_controller.h",
     "vr_gesture.h",
     "vr_gl_util.cc",
     "vr_gl_util.h",
     "vr_input_manager.cc",
@@ skipping 42 matching lines @@
 
     deps = [
       ":vr_common",
       "//base/test:run_all_unittests",
       "//base/test:test_support",
       "//testing/gtest",
       "//ui/gfx/geometry",
     ]
   }
 }