mash: Migrate some system user files to common.

ash/ash.gyp

Index: ash/ash.gyp
diff --git a/ash/ash.gyp b/ash/ash.gyp
index 0244662172a74f58c1cd8582d1d63528aae8c9cd..8e02a40acc9585ebc75fcbfb968218c277f5286f 100644
--- a/ash/ash.gyp
+++ b/ash/ash.gyp
@@ -206,6 +206,15 @@
       'common/system/update/tray_update.cc',
       'common/system/update/tray_update.h',
       'common/system/update/update_observer.h',
+      'common/system/user/button_from_view.cc',
+      'common/system/user/button_from_view.h',
+      'common/system/user/login_status.cc',
+      'common/system/user/login_status.h',
+      'common/system/user/rounded_image_view.cc',
+      'common/system/user/rounded_image_view.h',
+      'common/system/user/tray_user_separator.cc',
+      'common/system/user/tray_user_separator.h',
+      'common/system/user/user_observer.h',
       'common/system/volume_control_delegate.h',
       'common/wm/always_on_top_controller.cc',
       'common/wm/always_on_top_controller.h',
@@ -618,19 +627,10 @@
       'system/tray/system_tray.h',
       'system/tray/system_tray_notifier.cc',
       'system/tray/system_tray_notifier.h',
-      'system/user/button_from_view.cc',
-      'system/user/button_from_view.h',
-      'system/user/login_status.cc',
-      'system/user/login_status.h',
-      'system/user/rounded_image_view.cc',
-      'system/user/rounded_image_view.h',
       'system/user/tray_user.cc',
       'system/user/tray_user.h',
-      'system/user/tray_user_separator.cc',
-      'system/user/tray_user_separator.h',
       'system/user/user_card_view.cc',
       'system/user/user_card_view.h',
-      'system/user/user_observer.h',
       'system/user/user_view.cc',
       'system/user/user_view.h',
       'system/web_notification/ash_popup_alignment_delegate.cc',