Put code in //services/window_manager in namespace window_manager

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 SERVICES_WINDOW_MANAGER_FOCUS_CONTROLLER_OBSERVER_H_
 #define SERVICES_WINDOW_MANAGER_FOCUS_CONTROLLER_OBSERVER_H_
 
 namespace mojo {
+class View;
+}
 
-class View;
+namespace window_manager {
 
 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;
+  virtual void OnViewActivated(mojo::View* gained_active,
+                               mojo::View* lost_active) = 0;
 
   // Called when focus moves from |lost_focus| to |gained_focus|.
-  virtual void OnViewFocused(View* gained_focus, View* lost_focus) = 0;
+  virtual void OnViewFocused(mojo::View* gained_focus,
+                             mojo::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) {}
+  virtual void OnAttemptToReactivateView(mojo::View* request_active,
+                                         mojo::View* actual_active) {}
 
  protected:
   virtual ~FocusControllerObserver() {}
 };
 
-}  // namespace mojo
+}  // namespace window_manager
 
 #endif  // SERVICES_WINDOW_MANAGER_FOCUS_CONTROLLER_OBSERVER_H_