Add basic tracing support to the gtest launcher

base/test/BUILD.gn

 # Copyright (c) 2013 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/ui.gni")
 import("//build/config/nacl/config.gni")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
@@ skipping 110 matching lines @@
     "values_test_util.cc",
     "values_test_util.h",
   ]
 
   if (is_ios) {
     sources += [ "launcher/unit_test_launcher_ios.cc" ]
   } else if (!is_nacl_nonsfi) {
     sources += [
       "launcher/test_launcher.cc",
       "launcher/test_launcher.h",
+      "launcher/test_launcher_tracer.cc",
+      "launcher/test_launcher_tracer.h",
       "launcher/test_results_tracker.cc",
       "launcher/unit_test_launcher.cc",
       "multiprocess_test.cc",
       "multiprocess_test_android.cc",
     ]
   }
 
   configs += [ "//build/config:precompiled_headers" ]
 
   data = [
@@ skipping 123 matching lines @@
 
 if (is_android) {
   generate_jni("base_unittests_jni_headers") {
     sources = [
       "android/java/src/org/chromium/base/ContentUriTestUtils.java",
       "android/java/src/org/chromium/base/TestUiThread.java",
     ]
     jni_package = "base"
   }
 }