chromeos: Move device shutdown handling out of chrome into ash

ash/BUILD.gn

Index: ash/BUILD.gn
diff --git a/ash/BUILD.gn b/ash/BUILD.gn
index 3fe326a0c1f1da06d07ce437b738cb4aa89fa3c4..6de7e50a6037a4a7ffbe1917cd38e58ae2973607 100644
--- a/ash/BUILD.gn
+++ b/ash/BUILD.gn
@@ -187,6 +187,8 @@ component("ash") {
     "common/shelf/wm_shelf_util.cc",
     "common/shelf/wm_shelf_util.h",
     "common/shell_delegate.h",
+    "common/shutdown_controller.cc",
+    "common/shutdown_controller.h",
     "common/system/accessibility_observer.h",
     "common/system/brightness_control_delegate.h",
     "common/system/chromeos/audio/audio_detailed_view.cc",
@@ -307,7 +309,6 @@ component("ash") {
     "common/system/chromeos/session/tray_session_length_limit.h",
     "common/system/chromeos/settings/tray_settings.cc",
     "common/system/chromeos/settings/tray_settings.h",
-    "common/system/chromeos/shutdown_policy_observer.h",
     "common/system/chromeos/supervised/custodian_info_tray_observer.h",
     "common/system/chromeos/supervised/tray_supervised_user.cc",
     "common/system/chromeos/supervised/tray_supervised_user.h",
@@ -810,8 +811,6 @@ component("ash") {
     "wm/session_state_animator.h",
     "wm/session_state_animator_impl.cc",
     "wm/session_state_animator_impl.h",
-    "wm/shutdown_client_proxy.cc",
-    "wm/shutdown_client_proxy.h",
     "wm/stacking_controller.cc",
     "wm/stacking_controller.h",
     "wm/system_gesture_event_filter.cc",