Reland again [Startup Tracing] Add --trace-config-file flag

components/BUILD.gn

 # 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/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 import("//tools/grit/repack.gni")
 
 # Collection of all components. You wouldn't link to this, but this is rather
@@ skipping 403 matching lines @@
   }
 
   if (!is_android && !is_ios) {
     deps += [
       "//components/audio_modem:unit_tests",
       "//components/copresence:unit_tests",
       "//components/feedback:unit_tests",
       "//components/proximity_auth:unit_tests",
       "//components/sessions:unit_tests",
       "//components/storage_monitor:unit_tests",
+      "//components/tracing:unit_tests",
     ]
   }
 
   if (is_chromeos) {
     deps += [ "//components/ownership:unit_tests" ]
   }
 
   # TODO(GYP) need this target.
   #'breakpad/app/crash_keys_win_unittest.cc',
 
@@ skipping 153 matching lines @@
 
   deps = [
     "//base",
     "//base/test:test_support_perf",
     "//testing/gtest",
     "//testing/perf",
     "//content/test:test_support",
     "//components/visitedlink/browser",
   ]
 }