Rename UserInfo method GetEmail to GetDisplayEmail.

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 3e77a74d804a33d03a481c68aa9cdf0042b4b821..44000bf985b42de382b18ba8c8ecc5e1fd19d258 100644
--- a/ash/common/system/user/tray_user_unittest.cc
+++ b/ash/common/system/user/tray_user_unittest.cc
@@ -259,7 +259,7 @@ TEST_F(TrayUserTest, MutiUserModeButtonClicks) {
   // Since the name is capitalized, the email should be different then the
   // user_id.
   EXPECT_NE(active_user->GetAccountId().GetUserEmail(),
-            second_user->GetEmail());
+            second_user->GetDisplayEmail());
   tray()->CloseSystemBubble();
 }