mash: Move status area overview button to //ash/common

ash/system/overview/overview_button_tray_unittest.cc

Index: ash/system/overview/overview_button_tray_unittest.cc
diff --git a/ash/system/overview/overview_button_tray_unittest.cc b/ash/system/overview/overview_button_tray_unittest.cc
index 9c926b55bfa090fe73025a1c4c43f4d21fd8de69..32f320e4054301da4fa2f3089568cc6502f31b2e 100644
--- a/ash/system/overview/overview_button_tray_unittest.cc
+++ b/ash/system/overview/overview_button_tray_unittest.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/overview/overview_button_tray.h"
+#include "ash/common/system/overview/overview_button_tray.h"
 
 #include "ash/common/ash_switches.h"
 #include "ash/common/login_status.h"
@@ -48,6 +48,7 @@ OverviewButtonTray* GetSecondaryTray() {
 
 }  // namespace
 
+// TODO(jamescook): Migrate to //ash/common/system. http://crbug.com/620955
 class OverviewButtonTrayTest : public test::AshTestBase {
  public:
   OverviewButtonTrayTest() {}