Move yet more from WmShell to Shell

ash/common/system/user/tray_user_unittest.cc

Index: ash/common/system/user/tray_user_unittest.cc
diff --git a/ash/common/system/user/tray_user_unittest.cc b/ash/common/system/user/tray_user_unittest.cc
index 74d0cae67370820a26db9cd731b8ea017ff14e9b..7b6c5476466fce942b423fd37aa3574287ccc30b 100644
--- a/ash/common/system/user/tray_user_unittest.cc
+++ b/ash/common/system/user/tray_user_unittest.cc
@@ -55,9 +55,7 @@ class TrayUserTest : public test::AshTestBase {
 
   // Accessors to various system components.
   SystemTray* tray() { return tray_; }
-  SessionController* controller() {
-    return WmShell::Get()->session_controller();
-  }
+  SessionController* controller() { return Shell::Get()->session_controller(); }
   TrayUser* tray_user(int index) { return tray_user_[index]; }
 
  private: