[ash-md] Fixed TriView to relayout child Views when their preferred size changed.

ash/common/system/tray/tri_view.cc

 // 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.
 
 #include "ash/common/system/tray/tri_view.h"
 
 #include "ash/common/system/tray/size_range_layout.h"
 #include "base/logging.h"
 #include "ui/views/border.h"
 #include "ui/views/layout/box_layout.h"
 #include "ui/views/layout/fill_layout.h"
 #include "ui/views/layout/layout_manager.h"
 
 namespace ash {
 namespace {
 
 // Converts TriView::Orientation values to views::BoxLayout::Orientation values.
 views::BoxLayout::Orientation GetOrientation(TriView::Orientation orientation) {
   switch (orientation) {
     case TriView::Orientation::HORIZONTAL:
       return views::BoxLayout::kHorizontal;
     case TriView::Orientation::VERTICAL:
       return views::BoxLayout::kVertical;
   }
   // Required for some compilers.
   NOTREACHED();
   return views::BoxLayout::kHorizontal;
 }
 
+// A View that will perform a layout if a child view's preferred size changes.
+class RelayoutView : public views::View {

[tdanderson, 2016/11/28 21:47:37]

Hm, I'm a bit surprised there isn't something like this in use somewhere else
already.

+ public:
+  RelayoutView() {}
+
+  // views::View:
+  void ChildPreferredSizeChanged(View* child) override { Layout(); }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(RelayoutView);
+};
+
 }  // namespace
 
 TriView::TriView() : TriView(0) {}
 
 TriView::TriView(int padding_between_containers)
     : TriView(Orientation::HORIZONTAL, padding_between_containers) {}
 
 TriView::TriView(Orientation orientation) : TriView(orientation, 0) {}
 
 TriView::TriView(Orientation orientation, int padding_between_containers)
     : box_layout_(new views::BoxLayout(GetOrientation(orientation),
                                        0,
                                        0,
                                        padding_between_containers)),
       start_container_layout_manager_(new SizeRangeLayout),
       center_container_layout_manager_(new SizeRangeLayout),
       end_container_layout_manager_(new SizeRangeLayout) {
-  AddChildView(new views::View);
-  AddChildView(new views::View);
-  AddChildView(new views::View);
+  AddChildView(new RelayoutView);
+  AddChildView(new RelayoutView);
+  AddChildView(new RelayoutView);
 
   GetContainer(Container::START)
       ->SetLayoutManager(GetLayoutManager(Container::START));
   GetContainer(Container::CENTER)
       ->SetLayoutManager(GetLayoutManager(Container::CENTER));
   GetContainer(Container::END)
       ->SetLayoutManager(GetLayoutManager(Container::END));
 
   box_layout_->set_cross_axis_alignment(
       views::BoxLayout::CROSS_AXIS_ALIGNMENT_START);
@@ skipping 78 matching lines @@
       return center_container_layout_manager_;
     case Container::END:
       return end_container_layout_manager_;
   }
   // Required for some compilers.
   NOTREACHED();
   return nullptr;
 }
 
 }  // namespace ash