[Sync] Refactor SessionsSyncManager unit tests

components/sync_sessions/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.
 
 static_library("sync_sessions") {
   sources = [
     "favicon_cache.cc",
     "favicon_cache.h",
     "local_session_event_router.h",
     "lost_navigations_recorder.cc",
@@ skipping 82 matching lines @@
   sources = [
     "favicon_cache_unittest.cc",
     "lost_navigations_recorder_unittest.cc",
     "revisit/bookmarks_page_revisit_observer_unittest.cc",
     "revisit/current_tab_matcher_unittest.cc",
     "revisit/offset_tab_matcher_unittest.cc",
     "revisit/page_revisit_broadcaster_unittest.cc",
     "revisit/sessions_page_revisit_observer_unittest.cc",
     "revisit/typed_url_page_revisit_task_unittest.cc",
     "session_data_type_controller_unittest.cc",
+    "sessions_sync_manager_unittest.cc",
     "sync_sessions_metrics_unittest.cc",
     "synced_session_tracker_unittest.cc",
     "tab_node_pool_unittest.cc",
   ]
 
   deps = [
     ":sync_sessions",
     ":test_support",
     "//base/test:test_support",
     "//components/bookmarks/browser",
     "//components/history/core/browser",
     "//components/prefs:test_support",
     "//components/sessions:test_support",
     "//components/sync",
     "//components/sync:test_support_driver",
     "//components/sync:test_support_engine",
     "//components/sync:test_support_model",
     "//testing/gmock",
     "//testing/gtest",
     "//ui/base:base",
     "//url",
   ]
 }