Divide Cookie Store IOS tests into different files

ios/net/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.
 
 import("//ios/build/config.gni")
 import("//testing/test.gni")
 import("//url/features.gni")
 
 group("all_tests") {
   testonly = true
@@ skipping 61 matching lines @@
     "//base",
     "//base/test:run_all_unittests",
     "//net:test_support",
     "//testing/gtest",
     "//url",
   ]
 
   sources = [
     "cookies/cookie_cache_unittest.cc",
     "cookies/cookie_creation_time_manager_unittest.mm",
+    "cookies/cookie_store_ios_persistent_unittest.mm",
+    "cookies/cookie_store_ios_test_util.h",
+    "cookies/cookie_store_ios_test_util.mm",
     "cookies/cookie_store_ios_unittest.mm",
     "cookies/system_cookie_util_unittest.mm",
     "http_response_headers_util_unittest.mm",
     "nsurlrequest_util_unittest.mm",
     "protocol_handler_util_unittest.mm",
     "url_scheme_util_unittest.mm",
   ]
 
   assert_no_deps = ios_assert_no_deps
 }