Enable virtual keyboard in overview mode

ash/ash.gyp

 # Copyright (c) 2012 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.
 
 {
   'variables': {
     'chromium_code': 1,
     'grit_out_dir': '<(SHARED_INTERMEDIATE_DIR)/chrome',
     # These files lists are shared with the GN build.
     'ash_sources': [
@@ skipping 462 matching lines @@
       'touch/touch_hud_projection.cc',
       'touch/touch_hud_projection.h',
       'touch/touch_observer_hud.cc',
       'touch/touch_observer_hud.h',
       'touch/touch_transformer_controller.cc',
       'touch/touch_transformer_controller.h',
       'touch/touch_uma.cc',
       'touch/touch_uma.h',
       'touch/touchscreen_util.cc',
       'touch/touchscreen_util.h',
+      'virtual_keyboard_observer.cc',
+      'virtual_keyboard_observer.h',
       'volume_control_delegate.h',
       'wm/app_list_controller.cc',
       'wm/app_list_controller.h',
       'wm/always_on_top_controller.cc',
       'wm/always_on_top_controller.h',
       'wm/ash_native_cursor_manager.cc',
       'wm/ash_native_cursor_manager.h',
       'wm/ash_focus_rules.cc',
       'wm/ash_focus_rules.h',
       'wm/boot_splash_screen_chromeos.cc',
@@ skipping 335 matching lines @@
       'system/tray/tray_details_view_unittest.cc',
       'system/user/tray_user_unittest.cc',
       'system/web_notification/ash_popup_alignment_delegate_unittest.cc',
       'system/web_notification/web_notification_tray_unittest.cc',
       'test/ash_test_helper_unittest.cc',
       'test/ash_unittests.cc',
       'tooltips/tooltip_controller_unittest.cc',
       'touch/touch_observer_hud_unittest.cc',
       'touch/touch_transformer_controller_unittest.cc',
       'touch/touchscreen_util_unittest.cc',
+      'virtual_keyboard_observer_unittest.cc',
       'wm/app_list_controller_unittest.cc',
       'wm/ash_native_cursor_manager_unittest.cc',
       'wm/dock/docked_window_layout_manager_unittest.cc',
       'wm/dock/docked_window_resizer_unittest.cc',
       'wm/drag_window_resizer_unittest.cc',
       'wm/gestures/overview_gesture_handler_unittest.cc',
       'wm/immersive_fullscreen_controller_unittest.cc',
       'wm/lock_layout_manager_unittest.cc',
       'wm/lock_state_controller_unittest.cc',
       'wm/maximize_mode/accelerometer_test_data_literals.cc',
@@ skipping 417 matching lines @@
       'conditions': [
         ['chromeos==1', {
           'dependencies': [
             '../ui/display/display.gyp:display',
           ],
         }],
       ],
     },
   ],
 }