Introduce lock_screen_apps to chrome/browser/chromeos

chrome/browser/chromeos/lock_screen_apps/state_controller.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_CONTROLLER_H_
+#define CHROME_BROWSER_CHROMEOS_LOCK_SCREEN_APPS_STATE_CONTROLLER_H_
+
+#include "base/lazy_instance.h"
+#include "base/observer_list.h"
+#include "chrome/browser/chromeos/lock_screen_apps/state_observer.h"
+#include "chrome/browser/chromeos/lock_screen_apps/types.h"
+
+namespace lock_screen_apps {
+
+class StateObserver;
+
+// Manages state of lock screen action handler apps, and notifies
+// interested parties as the state changes.
+// Currently assumes single supported action - NEW_NOTE.
+class StateController {
+ public:
+  static StateController* Get();
+
+  void AddObserver(StateObserver* observer);
+  void RemoveObserver(StateObserver* observer);
+
+  // Gets current state assiciated with the action.
+  ActionState GetActionState(Action action) const;
+
+  // Handles an action request - if the action handler is available, this will
+  // show an app window for the specified action.
+  bool HandleAction(Action action);
+
+  // If there are any active lock screen action handlers, moved their windows
+  // to background, to ensure lock screen UI is visible.
+  void MoveToBackground();
+
+ private:
+  friend struct base::LazyInstanceTraitsBase<StateController>;
+
+  StateController();
+  ~StateController();
+
+  // Requests action state change to |state|.
+  // Returns whether the action state has changed.
+  bool UpdateActionState(Action action, ActionState state);
+
+  // notifies observers that an action state changed.
+  void NotifyStateChanged(Action action);
+
+  // New note action state.
+  ActionState new_note_state_ = ActionState::kNotSupported;
+
+  base::ObserverList<StateObserver> observers_;
+
+  DISALLOW_COPY_AND_ASSIGN(StateController);
+};
+
+}  // namespace lock_screen_apps
+
+#endif  // CHROME_BROWSER_CHROMEOS_LOCK_SCREEN_APPS_STATE_CONTROLLER_H_