Introduce lock_screen_apps to chrome/browser/chromeos

chrome/browser/chromeos/lock_screen_apps/state_observer.h

+// Copyright 2017 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_CHROMEOS_LOCK_SCREEN_APPS_STATE_OBSERVER_H_
+#define CHROME_BROWSER_CHROMEOS_LOCK_SCREEN_APPS_STATE_OBSERVER_H_
+
+#include "chrome/browser/chromeos/lock_screen_apps/types.h"
+
+namespace lock_screen_apps {
+
+// Interface that can be used to observe lock screen apps state.
+class StateObserver {
+ public:
+  virtual ~StateObserver() {}
+
+  // Invoked when the state of support for app provided lock screen actions
+  // changes.
+  // |states|: Maps actions supported by the platform to their current state.
+  virtual void OnLockScreenAppsStateChanged(Action action,
+                                            ActionState state) = 0;
+};
+
+}  // namespace lock_screen_apps
+
+#endif  // CHROME_BROWSER_CHROMEOS_LOCK_SCREEN_APPS_STATE_OBSERVER_H_