Fix shelf layout when switching from left-aligned shelf to right-aligned shelf

ash/system/status_area_widget_delegate.cc

 // Copyright (c) 2012 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.
 
 #include "ash/system/status_area_widget_delegate.h"
 
 #include "ash/ash_export.h"
 #include "ash/common/ash_switches.h"
 #include "ash/common/focus_cycler.h"
 #include "ash/common/material_design/material_design_controller.h"
@@ skipping 145 matching lines @@
       is_first_visible_child = false;
       layout->StartRow(0, 0);
       layout->AddView(child);
     }
   }
 
   layer()->GetAnimator()->StopAnimating();
   StatusAreaWidgetDelegateAnimationSettings settings(layer());
 
   Layout();
+  View::InvalidateLayout();

[James Cook, 2016/06/29 21:23:37]

It seems a little weird to call View::Layout() then immediately call
View::InvalidateLayout().

If you need to invalidate the layout of all the parent views, it might work to
call it at the start of UpdateLayout(). If that works, it is what I would
prefer.

If you really have to do it after Layout() there is probably only one specific
case where you need it (like after the call to UpdateLayout in
StatusAreaWidget::SetShelfAlignment()).

Either way this needs a comment explaining why you have to do it.

Also, you don't need View::.

   UpdateWidgetSize();
 }
 
 void StatusAreaWidgetDelegate::ChildPreferredSizeChanged(View* child) {
   // Need to resize the window when trays or items are added/removed.
   StatusAreaWidgetDelegateAnimationSettings settings(layer());
   UpdateWidgetSize();
 }
 
 void StatusAreaWidgetDelegate::ChildVisibilityChanged(View* child) {
@@ skipping 46 matching lines @@
       bottom_edge =
           on_edge ? GetTrayConstant(TRAY_PADDING_FROM_EDGE_OF_SHELF) : 0;
       right_edge = shelf_size - kShelfItemInset - item_height;
     }
   }
   child->SetBorder(views::Border::CreateEmptyBorder(top_edge, left_edge,
                                                     bottom_edge, right_edge));
 }
 
 }  // namespace ash