Make `chrome` target build without unused data members on Linux.

chrome/browser/password_manager/native_backend_gnome_x.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_PASSWORD_MANAGER_NATIVE_BACKEND_GNOME_X_H_
 #define CHROME_BROWSER_PASSWORD_MANAGER_NATIVE_BACKEND_GNOME_X_H_
 
 // libgnome-keyring has been deprecated in favor of libsecret.
 // See: https://mail.gnome.org/archives/commits-list/2013-October/msg08876.html
 //
@@ skipping 130 matching lines @@
                         ScopedVector<autofill::PasswordForm>* forms)
       WARN_UNUSED_RESULT;
 
   // Removes password created/synced in the time interval. Returns |true| if the
   // operation succeeded. |changes| will contain the changes applied.
   bool RemoveLoginsBetween(base::Time get_begin,
                            base::Time get_end,
                            TimestampToCompare date_to_compare,
                            password_manager::PasswordStoreChangeList* changes);
 
-  // The local profile id, used to generate the app string.
-  const LocalProfileId profile_id_;
-
   // The app string, possibly based on the local profile id.
   std::string app_string_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeBackendGnome);
 };
 
 #endif  // CHROME_BROWSER_PASSWORD_MANAGER_NATIVE_BACKEND_GNOME_X_H_