Changes view manager to report visibility and drawn state

mojo/services/view_manager/server_view_delegate.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_VIEW_MANAGER_SERVER_VIEW_DELEGATE_H_
 #define MOJO_SERVICES_VIEW_MANAGER_SERVER_VIEW_DELEGATE_H_
 
 #include "mojo/services/view_manager/view_manager_export.h"
 
 namespace gfx {
 class Rect;
 }
 
 namespace mojo {
 namespace service {
 
 class ServerView;
 
 class MOJO_VIEW_MANAGER_EXPORT ServerViewDelegate {
  public:
   // Invoked at the end of the View's destructor (after it has been removed from
   // the hierarchy).
   virtual void OnViewDestroyed(const ServerView* view) = 0;
 
-  // Invoked when the hierarchy has changed.
+  virtual void OnWillChangeViewHierarchy(const ServerView* view,
+                                         const ServerView* new_parent,
+                                         const ServerView* old_parent) = 0;
+
   virtual void OnViewHierarchyChanged(const ServerView* view,
                                       const ServerView* new_parent,
                                       const ServerView* old_parent) = 0;
 
   virtual void OnViewBoundsChanged(const ServerView* view,
                                    const gfx::Rect& old_bounds,
                                    const gfx::Rect& new_bounds) = 0;
 
   virtual void OnViewBitmapChanged(const ServerView* view) = 0;
 
+  virtual void OnWillChangeViewVisibility(const ServerView* view) = 0;
+
  protected:
   virtual ~ServerViewDelegate() {}
 };
 
 }  // namespace service
 }  // namespace mojo
 
 #endif  // MOJO_SERVICES_VIEW_MANAGER_SERVER_VIEW_DELEGATE_H_