Remove references to IsNewAvatarMenu since the flag was removed.

This CL removes all references of the new-avatar-menu flag since it's
no longer used. The new avatar menu is always shown on desktop and never
on Mobile and ChromeOS.

BUG=517582

Review URL: https://codereview.chromium.org/1307093004

Cr-Commit-Position: refs/heads/master@{#352041}
diff --git a/chrome/browser/browser_process_impl.cc b/chrome/browser/browser_process_impl.cc
index 7001e103..fecf890 100644
--- a/chrome/browser/browser_process_impl.cc
+++ b/chrome/browser/browser_process_impl.cc
@@ -283,8 +283,7 @@
                  "BrowserProcessImpl::StartTearDown:ProfileManager");
     // The desktop User Manager needs to be closed before the guest profile
     // can be destroyed.
-    if (switches::IsNewAvatarMenu())
-      UserManager::Hide();
+    UserManager::Hide();
     profile_manager_.reset();
   }