Reland: Remove aura and make a pure mojo::View version of FocusController.

mojo/services/window_manager/focus_controller_observer.h

+// Copyright 2014 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 MOJO_SERVICES_WINDOW_MANAGER_FOCUS_CONTROLLER_OBSERVER_H_
+#define MOJO_SERVICES_WINDOW_MANAGER_FOCUS_CONTROLLER_OBSERVER_H_
+
+namespace mojo {
+
+class View;
+
+class FocusControllerObserver {
+ public:
+  // Called when |active| gains focus, or there is no active view
+  // (|active| is null in this case.) |old_active| refers to the
+  // previous active view or null if there was no previously active
+  // view.
+  virtual void OnViewActivated(View* gained_active,
+                               View* lost_active) = 0;
+
+  // Called when focus moves from |lost_focus| to |gained_focus|.
+  virtual void OnViewFocused(View* gained_focus, View* lost_focus) = 0;
+
+  // Called when during view activation the currently active view is
+  // selected for activation. This can happen when a view requested for
+  // activation cannot be activated because a system modal view is active.
+  virtual void OnAttemptToReactivateView(View* request_active,
+                                         View* actual_active) {}
+
+ protected:
+  virtual ~FocusControllerObserver() {}
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_SERVICES_WINDOW_MANAGER_FOCUS_CONTROLLER_OBSERVER_H_