Introduce ash mojo interface for lock screen action handlers

ash/tray_action_handler/tray_action_handler_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 ASH_TRAY_ACTION_HANDLER_TRAY_ACTION_HANDLER_CONTROLLER_H_
+#define ASH_TRAY_ACTION_HANDLER_TRAY_ACTION_HANDLER_CONTROLLER_H_
+
+#include "ash/public/interfaces/tray_action_handler.mojom.h"
+#include "base/macros.h"
+#include "base/observer_list.h"
+#include "mojo/public/cpp/bindings/binding_set.h"
+
+namespace ash {
+
+class TrayActionHandlerObserver;
+
+// Controller that ash can use to request a predefined set of actions to be
+// performed by clients.
+// The controller provides an interface to:
+//  * Send a request to the client to handle an action.
+//  * Observe the state of support for an action as reported by the current ash
+//    client.
+// Currently, only single action is supported - creating new note on the lock
+// screen.
+class TrayActionHandlerController : public mojom::TrayActionHandlerController {
+ public:
+  TrayActionHandlerController();
+  ~TrayActionHandlerController() override;
+
+  void AddObserver(TrayActionHandlerObserver* observer);
+  void RemoveObserver(TrayActionHandlerObserver* observer);
+
+  void BindRequest(mojom::TrayActionHandlerControllerRequest request);
+
+  // Gets last known handler state for the action.
+  // It will return kNotSupported if an action handler has not been set using
+  // |SetClient|.
+  mojom::TrayActionHandlerState GetState(mojom::TrayActionHandlerAction action);
+
+  // If an action handler is set, send it a request to handle the action.
+  void RequestHandleAction(mojom::TrayActionHandlerAction action);
+
+  // mojom::TrayActionHandlerController impl:

[James Cook, 2017/05/03 23:31:51]

super-nit: Just "mojom::TrayActionHandlerController:" or
"mojom::TrayActionHandlerController overrides:"

[tbarzic, 2017/05/04 20:58:30]

Done.

+  void SetClient(mojom::TrayActionHandlerClientPtr action_handler) override;
+  void UpdateActionHandlerState(mojom::TrayActionHandlerAction action,
+                                mojom::TrayActionHandlerState state) override;
+
+ private:
+  // Notifies the observers that state for the action has been updated.
+  void NotifyActionStateChanged(mojom::TrayActionHandlerAction action);
+
+  // Last known state for new_note action.
+  mojom::TrayActionHandlerState new_note_state_ =
+      mojom::TrayActionHandlerState::kNotSupported;
+
+  base::ObserverList<TrayActionHandlerObserver> observers_;
+
+  mojo::BindingSet<mojom::TrayActionHandlerController> bindings_;
+
+  mojom::TrayActionHandlerClientPtr action_handler_client_;
+
+  DISALLOW_COPY_AND_ASSIGN(TrayActionHandlerController);
+};
+
+}  // namespace ash
+
+#endif  // ASH_TRAY_ACTION_HANDLER_TRAY_ACTION_HANDLER_CONTROLLER_H_