Introduce ash mojo interface for lock screen action handlers

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 <memory>
+
+#include "ash/public/interfaces/tray_action.mojom.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"
+#include "mojo/public/cpp/bindings/binding.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 {
+class StateController : public ash::mojom::TrayActionClient {
  public:
+  // Returns whether the StateController is enabled - it is currently guarded by
+  // a feature flag. If not enabled, |StateController| instance is not allowed
+  // to be created. |Get| will still work, but it will return nullptr.
+  static bool IsEnabled();
+
+  // Returns the global StateController instance. Note that this can return
+  // nullptr when lock screen apps are not enabled (see |IsEnabled|).
   static StateController* Get();
 
+  // Note that only one StateController is allowed per process. Creating a
+  // StateController will set global instance ptr that can be accessed using
+  // |Get|. This pointer will be reset when the StateController is destroyed.
+  StateController();
+  ~StateController() override;
+
+  // Sets the tray action that should be used by |StateController|.
+  // Has to be called before |Initialize|.
+  void SetTrayActionPtrForTesting(ash::mojom::TrayActionPtr tray_action_ptr);
+  void FlushTrayActionForTesting();
+
+  // Initializes mojo bindings for the StateController - it creates binding to
+  // ash's tray action interface and sets this object as the interface's client.
+  void Initialize();
+
   void AddObserver(StateObserver* observer);
   void RemoveObserver(StateObserver* observer);
 
-  // Gets current state assiciated with the action.
-  ActionState GetActionState(Action action) const;
+  // Gets current state assiciated with the lock screen note action.
+  ash::mojom::TrayActionState GetLockScreenNoteState() 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);
+  // ash::mojom::TrayActionClient:
+  void RequestNewLockScreenNote() override;
 
   // If there are any active lock screen action handlers, moved their windows
   // to background, to ensure lock screen UI is visible.
   void MoveToBackground();
 
+  // Sets the current state - to be used in tests. Hopefully, when this class
+  // has more logic implemented, this will not be needed.
+  void SetLockScreenNoteStateForTesting(ash::mojom::TrayActionState state);
+
  private:
-  friend struct base::LazyInstanceTraitsBase<StateController>;
+  // Requests lock screen note action state change to |state|.
+  // Returns whether the action state has changed.
+  bool UpdateLockScreenNoteState(ash::mojom::TrayActionState state);
 
-  StateController();
-  ~StateController();
+  // Notifies observers that the lock screen note action state changed.
+  void NotifyLockScreenNoteStateChanged();
 
-  // 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;
+  // Lock screen note action state.
+  ash::mojom::TrayActionState lock_screen_note_state_ =
+      ash::mojom::TrayActionState::kNotAvailable;
 
   base::ObserverList<StateObserver> observers_;
 
+  mojo::Binding<ash::mojom::TrayActionClient> binding_;
+  ash::mojom::TrayActionPtr tray_action_ptr_;
+
   DISALLOW_COPY_AND_ASSIGN(StateController);
 };
 
 }  // namespace lock_screen_apps
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOCK_SCREEN_APPS_STATE_CONTROLLER_H_