cros: Pull TestLockScreenClient into a separate MockLockScreenClient file.

ash/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/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 import("//ui/base/ui_features.gni")
 
 # Historical note: Ash shipped on Windows for a couple years to support
@@ skipping 1150 matching lines @@
     "first_run/first_run_helper_unittest.cc",
     "focus_cycler_unittest.cc",
     "frame/caption_buttons/frame_caption_button_container_view_unittest.cc",
     "frame/caption_buttons/frame_size_button_unittest.cc",
     "frame/custom_frame_view_ash_unittest.cc",
     "frame/default_header_painter_unittest.cc",
     "laser/laser_pointer_controller_unittest.cc",
     "laser/laser_pointer_points_unittest.cc",
     "laser/laser_segment_utils_unittest.cc",
     "login/lock_screen_controller_unittest.cc",
+    "login/mock_lock_screen_client.cc",
+    "login/mock_lock_screen_client.h",
     "metrics/desktop_task_switch_metric_recorder_unittest.cc",
     "metrics/pointer_metrics_recorder_unittest.cc",
     "metrics/task_switch_metrics_recorder_unittest.cc",
     "metrics/task_switch_time_tracker_unittest.cc",
     "metrics/user_metrics_recorder_unittest.cc",
     "mus/window_manager_common_unittests.cc",
     "mus_property_mirror_ash_unittest.cc",
     "root_window_controller_unittest.cc",
     "rotator/screen_rotation_animation_unittest.cc",
     "rotator/screen_rotation_animator_unittest.cc",
@@ skipping 333 matching lines @@
     "//content/public/app:both",
     "//device/bluetooth",
   ]
 
   data_deps = [
     "//ash/strings:ash_test_strings",
     "//ash/resources:ash_test_resources_with_content_100_percent",
     "//ash/resources:ash_test_resources_200_percent",
   ]
 }