linux: Add empty implementation of auto updater.

atom.gyp

@@ -66,6 +66,7 @@
       'browser/auto_updater.h',
       'browser/auto_updater_delegate.cc',
       'browser/auto_updater_delegate.h',
+      'browser/auto_updater_linux.cc',
       'browser/auto_updater_mac.mm',
       'browser/auto_updater_win.cc',
       'browser/atom_application_mac.h',

browser/auto_updater_linux.cc

@@ -0,0 +1,33 @@
+// Copyright (c) 2013 GitHub, Inc. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "browser/auto_updater.h"
+
+namespace auto_updater {
+
+// static
+void AutoUpdater::Init() {
+}
+
+// static
+void AutoUpdater::SetFeedURL(const std::string& url) {
+}
+
+// static
+void AutoUpdater::SetAutomaticallyChecksForUpdates(bool yes) {
+}
+
+// static
+void AutoUpdater::SetAutomaticallyDownloadsUpdates(bool yes) {
+}
+
+// static
+void AutoUpdater::CheckForUpdates() {
+}
+
+// static
+void AutoUpdater::CheckForUpdatesInBackground() {
+}
+
+}  // namespace auto_updater