Add lots of testonly annotations to the GN build.

google_apis/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")
 
 declare_args() {
   # You can set the variable 'use_official_google_api_keys' to true
   # to use the Google-internal file containing official API keys
   # for Google Chrome even in a developer build.  Setting this
@@ skipping 151 matching lines @@
       "drive/request_util.h",
       "drive/task_util.cc",
       "drive/task_util.h",
       "drive/time_util.cc",
       "drive/time_util.h",
     ]
   }
 }
 
 source_set("test_support") {
+  testonly = true
   sources = [
     "gaia/fake_gaia.cc",
     "gaia/fake_gaia.h",
     "gaia/fake_identity_provider.cc",
     "gaia/fake_identity_provider.h",
     "gaia/fake_oauth2_token_service.cc",
     "gaia/fake_oauth2_token_service.h",
     "gaia/mock_url_fetcher_factory.h",
     "gaia/oauth2_token_service_test_util.cc",
     "gaia/oauth2_token_service_test_util.h",
@@ skipping 53 matching lines @@
       "drive/drive_api_url_generator_unittest.cc",
       "drive/gdata_wapi_parser_unittest.cc",
       "drive/gdata_wapi_requests_unittest.cc",
       "drive/gdata_wapi_url_generator_unittest.cc",
       "drive/request_sender_unittest.cc",
       "drive/request_util_unittest.cc",
       "drive/time_util_unittest.cc",
     ]
   }
 }