VR: Add a native UI element scene manager

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("//device/vr/features.gni")
 import("//testing/test.gni")
 
 assert(enable_vr)
@@ skipping 16 matching lines @@
       "mailbox_to_surface_bridge.cc",
       "mailbox_to_surface_bridge.h",
       "non_presenting_gvr_delegate.cc",
       "non_presenting_gvr_delegate.h",
       "ui_element.cc",
       "ui_element.h",
       "ui_interface.cc",
       "ui_interface.h",
       "ui_scene.cc",
       "ui_scene.h",
+      "ui_scene_manager.cc",
+      "ui_scene_manager.h",
       "vr_compositor.cc",
       "vr_compositor.h",
       "vr_controller.cc",
       "vr_controller.h",
       "vr_controller_model.cc",
       "vr_controller_model.h",
       "vr_gesture.h",
       "vr_gl_thread.cc",
       "vr_gl_thread.h",
       "vr_gl_util.cc",
@@ skipping 82 matching lines @@
     libs =
         [ "//third_party/gvr-android-sdk/libgvr_shim_static_${current_cpu}.a" ]
 
     data = [
       "test/data/sample_inline.gltf",
       "test/data/sample_external.gltf",
       "test/data/sample.bin",
     ]
   }
 }