Add enable_vr_shell build time flag and show icon in Daydream app luncher

chrome/android/chrome_public_apk_tmpl.gni

 # Copyright 2015 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("//base/android/linker/config.gni")
 import("//build/config/android/rules.gni")
 import("//chrome/common/features.gni")
 import("//third_party/leakcanary/config.gni")
 import("channel.gni")
 
@@ skipping 11 matching lines @@
   # until the number of 32 bit devices which don't support this
   # approach falls to a minimal level -  http://crbug.com/390618.
   chrome_public_apk_load_library_from_apk =
       chromium_linker_supported &&
       (current_cpu == "arm64" || current_cpu == "x64")
 }
 
 default_chrome_public_jinja_variables = [
   "channel=$android_channel",
   "enable_leakcanary=$enable_leakcanary",
+  "enable_vr_shell=$enable_vr_shell",
 ]
 
 # GYP: //chrome/android/chrome_apk.gypi
 template("chrome_public_apk_tmpl") {
   android_apk(target_name) {
     forward_variables_from(invoker, "*")
     _native_lib_file =
         rebase_path("$root_gen_dir/CHROME_VERSION.json", root_out_dir)
     native_lib_version_arg = "@FileArg($_native_lib_file:full-quoted)"
 
@@ skipping 23 matching lines @@
       if (!defined(load_library_from_apk)) {
         load_library_from_apk = chrome_public_apk_load_library_from_apk
       }
 
       if (!defined(enable_relocation_packing)) {
         enable_relocation_packing = chrome_public_apk_use_relocation_packer
       }
     }
   }
 }