Rename "test" ozone platform to "headless"

ui/ozone/ozone.gni

 # Copyright 2014 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/chromecast_build.gni")
 
 declare_args() {
   # Select platforms automatically. Turn this off for manual control.
   ozone_auto_platforms = true
 
   # This enables memory-mapped access to accelerated graphics buffers via the
   # VGEM ("virtual GEM") driver. This is currently only available on Chrome OS
   # kernels and affects code in the GBM ozone platform.
   # TODO(dshwang): remove this flag when all gbm hardware supports vgem map.
   # crbug.com/519587
   use_vgem_map = false
 }
 
 declare_args() {
   # The platform that will be active by default.
   ozone_platform = ""
 
   # Enable individual platforms.
   ozone_platform_caca = false
   ozone_platform_cast = false
   ozone_platform_egltest = false
   ozone_platform_gbm = false
   ozone_platform_ozonex = false
-  ozone_platform_test = false
+  ozone_platform_headless = false
 
   if (ozone_auto_platforms) {
     if (is_chromecast) {
       # The default platform used at runtime is "cast".
       ozone_platform = "cast"
       ozone_platform_cast = true
-      ozone_platform_test = true
+      ozone_platform_headless = true
 
       # For desktop Chromecast builds, override the default "cast" platform with
       # --ozone_platform=egltest
       if (target_os == "linux" && target_cpu != "arm") {
         ozone_platform_egltest = true
         ozone_platform_ozonex = true
       }
     } else {
-      # Use test as the default platform.
-      ozone_platform = "test"
+      # Use headless as the default platform.
+      ozone_platform = "headless"
 
       # Build all platforms whose deps are in install-build-deps.sh.
       # Only these platforms will be compile tested by buildbots.
       ozone_platform_gbm = true
-      ozone_platform_test = true
+      ozone_platform_headless = true
       ozone_platform_egltest = true
     }
   }
 }