Extract MockBrowsingDataRemover to separate file to make it possible to use it

chrome/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("//build/config/chrome_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
@@ skipping 4238 matching lines @@
     "browsing_data/mock_browsing_data_flash_lso_helper.cc",
     "browsing_data/mock_browsing_data_flash_lso_helper.h",
     "browsing_data/mock_browsing_data_indexed_db_helper.cc",
     "browsing_data/mock_browsing_data_indexed_db_helper.h",
     "browsing_data/mock_browsing_data_local_storage_helper.cc",
     "browsing_data/mock_browsing_data_local_storage_helper.h",
     "browsing_data/mock_browsing_data_media_license_helper.cc",
     "browsing_data/mock_browsing_data_media_license_helper.h",
     "browsing_data/mock_browsing_data_quota_helper.cc",
     "browsing_data/mock_browsing_data_quota_helper.h",
+    "browsing_data/mock_browsing_data_remover.cc",
+    "browsing_data/mock_browsing_data_remover.h",
     "browsing_data/mock_browsing_data_service_worker_helper.cc",
     "browsing_data/mock_browsing_data_service_worker_helper.h",
     "download/download_test_file_activity_observer.cc",
     "download/download_test_file_activity_observer.h",
     "history/history_test_utils.cc",
     "history/history_test_utils.h",
     "media/webrtc/fake_desktop_media_list.cc",
     "media/webrtc/fake_desktop_media_list.h",
     "net/dns_probe_test_util.cc",
     "net/dns_probe_test_util.h",
@@ skipping 273 matching lines @@
       "media/pepper_cdm_test_constants.cc",
       "media/pepper_cdm_test_constants.h",
     ]
   }
 }
 
 service_manifest("preferences_manifest") {
   name = "preferences"
   source = "prefs/preferences_manifest.json"
 }