mash: Migrate ash/system/user to ash/common.

ash/common/system/user/tray_user.cc

Index: ash/common/system/user/tray_user.cc
diff --git a/ash/system/user/tray_user.cc b/ash/common/system/user/tray_user.cc
similarity index 98%
rename from ash/system/user/tray_user.cc
rename to ash/common/system/user/tray_user.cc
index e0699c1a39ec6feefbb838c983226a11358595bd..463307698b310363c75518e2502f2af7ac992f28 100644
--- a/ash/system/user/tray_user.cc
+++ b/ash/common/system/user/tray_user.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ash/system/user/tray_user.h"
+#include "ash/common/system/user/tray_user.h"
 
 #include "ash/common/ash_switches.h"
 #include "ash/common/session/session_state_delegate.h"
@@ -13,9 +13,9 @@
 #include "ash/common/system/tray/tray_item_view.h"
 #include "ash/common/system/tray/tray_utils.h"
 #include "ash/common/system/user/rounded_image_view.h"
+#include "ash/common/system/user/user_view.h"
 #include "ash/common/wm_shell.h"
 #include "ash/system/tray/system_tray.h"
-#include "ash/system/user/user_view.h"
 #include "base/logging.h"
 #include "base/strings/string16.h"
 #include "components/signin/core/account_id/account_id.h"