[sync] Prevent sessions flare on startup

chrome/test/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/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
@@ skipping 3368 matching lines @@
     "../browser/signin/test_signin_client_builder.h",
     "../browser/ssl/chrome_expect_ct_reporter_unittest.cc",
     "../browser/ssl/security_state_tab_helper_unittest.cc",
     "../browser/ssl/ssl_error_handler_unittest.cc",
     "../browser/status_icons/status_icon_menu_model_unittest.cc",
     "../browser/status_icons/status_icon_unittest.cc",
     "../browser/status_icons/status_tray_unittest.cc",
     "../browser/storage/durable_storage_permission_context_unittest.cc",
     "../browser/subresource_filter/subresource_filter_content_settings_manager_factory_unittest.cc",
     "../browser/sync/profile_sync_service_factory_unittest.cc",
+    "../browser/sync/sessions/sync_sessions_web_contents_router_unittest.cc",
     "../browser/sync/sync_startup_tracker_unittest.cc",
     "../browser/task_profiler/task_profiler_data_serializer_unittest.cc",
     "../browser/thumbnails/content_analysis_unittest.cc",
     "../browser/thumbnails/content_based_thumbnailing_algorithm_unittest.cc",
     "../browser/thumbnails/simple_thumbnail_crop_unittest.cc",
     "../browser/thumbnails/thumbnail_service_unittest.cc",
     "../browser/translate/language_model_factory_unittest.cc",
     "../browser/translate/translate_service_unittest.cc",
     "../browser/ui/android/tab_model/tab_model_list_unittest.cc",
     "../browser/ui/android/tab_model/tab_model_unittest.cc",
@@ skipping 1843 matching lines @@
 }
 
 if (is_win) {
   loadable_module("conflicts_dll") {
     testonly = true
     sources = [
       "conflicts/conflicts_dll.cc",
     ]
   }
 }