chromeos: Introduce ash::SystemTrayTestApi

chrome/browser/ui/ash/system_tray_client_browsertest.cc

Index: chrome/browser/ui/ash/system_tray_client_browsertest.cc
diff --git a/chrome/browser/ui/ash/system_tray_client_browsertest.cc b/chrome/browser/ui/ash/system_tray_client_browsertest.cc
index 8a71e1b00b4827f014d651c716434621cbf876e2..63f22adcc3f501523b7b2879307711dc8f974caf 100644
--- a/chrome/browser/ui/ash/system_tray_client_browsertest.cc
+++ b/chrome/browser/ui/ash/system_tray_client_browsertest.cc
@@ -9,6 +9,7 @@
 #include "ash/system/enterprise/tray_enterprise.h"
 #include "ash/system/tray/label_tray_view.h"
 #include "ash/system/tray/system_tray.h"
+#include "ash/system/tray/system_tray_test_api.h"
 #include "ash/system/update/tray_update.h"
 #include "chrome/browser/chromeos/policy/device_policy_cros_browser_test.h"
 #include "chrome/browser/upgrade_detector.h"
@@ -69,7 +70,7 @@ IN_PROC_BROWSER_TEST_F(SystemTrayClientEnterpriseTest, TrayEnterprise) {
 
   // Managed devices show an item in the menu.
   ash::TrayEnterprise* tray_enterprise =
-      system_tray->GetTrayEnterpriseForTesting();
+      ash::SystemTrayTestApi(system_tray).tray_enterprise();
   ASSERT_TRUE(tray_enterprise->tray_view());
   EXPECT_TRUE(tray_enterprise->tray_view()->visible());