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 4211 matching lines @@
 
 # Use a static library here because many test binaries depend on this but don't
 # require many files from it. This makes linking more efficient.
 static_library("test_support") {
   testonly = true
 
   # Always include this via the main test support target.
   visibility = [ "//chrome/test:test_support" ]
 
   sources = [
+    "browsing_data/browsing_data_remover_mock.cc",
+    "browsing_data/browsing_data_remover_mock.h",
     "browsing_data/mock_browsing_data_appcache_helper.cc",
     "browsing_data/mock_browsing_data_appcache_helper.h",
     "browsing_data/mock_browsing_data_cache_storage_helper.cc",
     "browsing_data/mock_browsing_data_cache_storage_helper.h",
     "browsing_data/mock_browsing_data_channel_id_helper.cc",
     "browsing_data/mock_browsing_data_channel_id_helper.h",
     "browsing_data/mock_browsing_data_cookie_helper.cc",
     "browsing_data/mock_browsing_data_cookie_helper.h",
     "browsing_data/mock_browsing_data_database_helper.cc",
     "browsing_data/mock_browsing_data_database_helper.h",
@@ skipping 295 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"
 }