[ash] Made TriView's re-layout automatically when a child container's visibility changes.

ash/system/tray/tri_view.h

 // Copyright 2016 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_SYSTEM_TRAY_TRI_VIEW_H_
 #define ASH_SYSTEM_TRAY_TRI_VIEW_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
@@ skipping 83 matching lines @@
   // before allocating the remaining space to the container views.
   void SetInsets(const gfx::Insets& insets);
 
   // Sets the border for the given |container|.
   void SetContainerBorder(Container container,
                           std::unique_ptr<views::Border> border);
 
   // Sets whether the |container| is visible. During a layout the space will be
   // allocated to the visible containers only. i.e. non-visible containers will
   // not be allocated any space.
+  // Note: This will cause a relayout.
   void SetContainerVisible(Container container, bool visible);
 
   // Sets the flex weight for the given |container|. Using the preferred size as
   // the basis, free space along the main axis is distributed to views in the
   // ratio of their flex weights. Similarly, if the views will overflow the
   // parent, space is subtracted in these ratios.
   //
   // A flex of 0 means this view is not resized. Flex values must not be
   // negative.
   //
@@ skipping 34 matching lines @@
   // to manipulate the child views during construction/destruction so this flag
   // is used to disable the DCHECK during construction/destruction.
   bool enable_hierarchy_changed_dcheck_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(TriView);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_TRI_VIEW_H_