Vertically centered app list page switcher

ui/app_list/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/ui.gni")
 import("//testing/test.gni")
 
 component("app_list") {
   sources = [
     "app_list_constants.cc",
@@ skipping 112 matching lines @@
       "views/contents_view.h",
       "views/custom_launcher_page_view.cc",
       "views/custom_launcher_page_view.h",
       "views/folder_background_view.cc",
       "views/folder_background_view.h",
       "views/folder_header_view.cc",
       "views/folder_header_view.h",
       "views/folder_header_view_delegate.h",
       "views/image_shadow_animator.cc",
       "views/image_shadow_animator.h",
-      "views/page_switcher.cc",
       "views/page_switcher.h",
+      "views/page_switcher_horizontal.cc",
+      "views/page_switcher_horizontal.h",
+      "views/page_switcher_vertical.cc",
+      "views/page_switcher_vertical.h",
       "views/pulsing_block_view.cc",
       "views/pulsing_block_view.h",
       "views/search_box_view.cc",
       "views/search_box_view.h",
       "views/search_box_view_delegate.h",
       "views/search_result_actions_view.cc",
       "views/search_result_actions_view.h",
       "views/search_result_actions_view_delegate.h",
       "views/search_result_answer_card_view.cc",
       "views/search_result_answer_card_view.h",
@@ skipping 129 matching lines @@
       "views/speech_view_unittest.cc",
       "views/test/apps_grid_view_test_api.cc",
       "views/test/apps_grid_view_test_api.h",
     ]
     deps += [
       "//ui/views",
       "//ui/views:test_support",
     ]
   }
 }