Fixed non-speaking Sign out buttons.

ash/system/logout_button/tray_logout_button.cc

Index: ash/system/logout_button/tray_logout_button.cc
diff --git a/ash/system/logout_button/tray_logout_button.cc b/ash/system/logout_button/tray_logout_button.cc
index 9820c40d415772329b0ac6081246396e38565ce8..202652978d1b19c36aeb9ab894c52a90b4595a13 100644
--- a/ash/system/logout_button/tray_logout_button.cc
+++ b/ash/system/logout_button/tray_logout_button.cc
@@ -86,7 +86,10 @@ class LogoutButton : public views::LabelButton,
 
   void OnLoginStatusChanged(user::LoginStatus status) {
     login_status_ = status;
-    SetText(GetLocalizedSignOutStringForStatus(login_status_, false));
+    const string16 title = GetLocalizedSignOutStringForStatus(login_status_,
+                                                              false);
+    SetText(title);
+    SetAccessibleName(title);
     UpdateVisibility();
   }