Use mojo SystemTray interfaces for both mash and classic ash

chrome/browser/ui/ash/system_tray_delegate_chromeos_browsertest_chromeos.cc

Index: chrome/browser/ui/ash/system_tray_delegate_chromeos_browsertest_chromeos.cc
diff --git a/chrome/browser/ui/ash/system_tray_delegate_chromeos_browsertest_chromeos.cc b/chrome/browser/ui/ash/system_tray_delegate_chromeos_browsertest_chromeos.cc
index f57079ab841fdccbaecdd792569b1f723ad6fad0..8d6958b53cae371740a454438293f71ef4267de4 100644
--- a/chrome/browser/ui/ash/system_tray_delegate_chromeos_browsertest_chromeos.cc
+++ b/chrome/browser/ui/ash/system_tray_delegate_chromeos_browsertest_chromeos.cc
@@ -91,6 +91,8 @@ class SystemTrayDelegateChromeOSTest : public LoginManagerTest {
         user_manager::UserManager::Get()->FindUser(account_id);
     Profile* profile = ProfileHelper::Get()->GetProfileByUser(user);
     profile->GetPrefs()->SetBoolean(prefs::kUse24HourClock, use_24_hour_clock);
+    // Allow clock setting to be sent to ash over mojo.
+    content::RunAllPendingInMessageLoop();
   }
 
   const AccountId account_id1_;
@@ -114,13 +116,17 @@ IN_PROC_BROWSER_TEST_F(SystemTrayDelegateChromeOSTest,
   SetupUserProfile(account_id1_, true /* Use_24_hour_clock. */);
   CreateDefaultView();
   EXPECT_EQ(base::k24HourClock, GetHourType());
+
   UserAddingScreen::Get()->Start();
   content::RunAllPendingInMessageLoop();
   AddUser(account_id2_.GetUserEmail());
   SetupUserProfile(account_id2_, false /* Use_24_hour_clock. */);
   CreateDefaultView();
   EXPECT_EQ(base::k12HourClock, GetHourType());
+
   user_manager::UserManager::Get()->SwitchActiveUser(account_id1_);
+  // Allow clock setting to be sent to ash over mojo.
+  content::RunAllPendingInMessageLoop();
   CreateDefaultView();
   EXPECT_EQ(base::k24HourClock, GetHourType());
 }