Mark gtest and gmock as testonly in GN.

components/autofill/content/browser/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("//third_party/protobuf/proto_library.gni")
 
 # GYP version: components/autofill.gypi:autofill_content_browser
 static_library("browser") {
   sources = [
     "content_autofill_driver.cc",
@@ skipping 60 matching lines @@
 }
 
 proto_library("risk_proto") {
   sources = [
     "risk/proto/fingerprint.proto",
   ]
   proto_out_dir = "components/autofill/content/browser/risk/proto"
 }
 
 static_library("test_support") {
+  testonly = true
   sources = [
     "wallet/mock_wallet_client.cc",
     "wallet/mock_wallet_client.h",
     "wallet/wallet_test_util.cc",
     "wallet/wallet_test_util.h",
   ]
 
   deps = [
     "//testing/gmock",
   ]
 }
 
 source_set("unit_tests") {
+  testonly = true
   sources = [
     "content_autofill_driver_unittest.cc",
     "request_autocomplete_manager_unittest.cc",
     "wallet/full_wallet_unittest.cc",
     "wallet/instrument_unittest.cc",
     "wallet/wallet_address_unittest.cc",
     "wallet/wallet_client_unittest.cc",
     "wallet/wallet_items_unittest.cc",
     "wallet/wallet_service_url_unittest.cc",
     "wallet/wallet_signin_helper_unittest.cc",
   ]
 
   deps = [
     ":browser",
     ":test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }