Ported telemetry_gpu_test target to Android.

tools/perf/BUILD.gn

 # 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.
 
 if (!is_android) {
   group("perf") {
+    testonly = true
     deps = [
       "//tools/perf/chrome_telemetry_build:telemetry_chrome_test",
     ]
 
     data = [
       "//tools/perf/",
 
       # Field trial config
       "//tools/variations/",
       "//testing/variations/",
     ]
   }
 }
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 
   wrapper_script("run_benchmark_wrapper") {
     target = "run_benchmark"
     flag_name = "--chromium-output-directory"
   }
 }