Implement new compositor and ContentViewCore reparenting for VR Shell.

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")
 
 assert(enable_vr_shell && android_java_ui)
 
 static_library("vr_shell") {
   sources = [
     "ui_elements.cc",
     "ui_elements.h",
+    "vr_compositor.cc",
+    "vr_compositor.h",
     "vr_shell.cc",
     "vr_shell.h",
     "vr_shell_renderer.cc",
     "vr_shell_renderer.h",
     "vr_util.cc",
     "vr_util.h",
   ]
 
   deps = [
     ":vr_shell_jni_headers",
     "//base",
     "//device/vr",
     "//third_party/gvr-android-sdk:gvr_base_java",
     "//third_party/gvr-android-sdk:gvr_common_java",
     "//third_party/gvr-android-sdk:libgvr",
     "//ui/gl",
     "//ui/gl/init",
   ]
 
   configs += [ "//third_party/gvr-android-sdk:libgvr_config" ]
 }
 
 generate_jni("vr_shell_jni_headers") {
   sources = [
     "//chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShell.java",
   ]
   jni_package = "vr_shell"
 }