Use GridLayout for DialogClientView's button row.

ui/views/examples/dialog_example.cc

 // Copyright 2017 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 "ui/views/examples/dialog_example.h"
 
 #include "base/macros.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/views/bubble/bubble_dialog_delegate.h"
 #include "ui/views/controls/button/checkbox.h"
@@ skipping 227 matching lines @@
 
 void DialogExample::ResizeDialog() {
   DCHECK(last_dialog_);
   Widget* widget = last_dialog_->GetWidget();
   gfx::Rect preferred_bounds(widget->GetRestoredBounds());
   preferred_bounds.set_size(widget->non_client_view()->GetPreferredSize());
 
   // Q: Do we need NonClientFrameView::GetWindowBoundsForClientBounds() here?
   // A: When DialogCientView properly feeds back sizes, we do not.
   widget->SetBoundsConstrained(preferred_bounds);
+
+  // For user-resizable dialogs, ensure the window manager enforces any new
+  // minimum size.
+  widget->OnSizeConstraintsChanged();
 }
 
 void DialogExample::ButtonPressed(Button* sender, const ui::Event& event) {
   if (sender == show_) {
     if (bubble_->checked()) {
       Bubble* bubble = new Bubble(this, sender);
       last_dialog_ = bubble;
       BubbleDialogDelegateView::CreateBubble(bubble);
     } else {
       Dialog* dialog = new Dialog(this);
       last_dialog_ = dialog;
       dialog->InitDelegate();
 
       // constrained_window::CreateBrowserModalDialogViews() allows dialogs to
       // be created as MODAL_TYPE_WINDOW without specifying a parent.
       gfx::NativeView parent = nullptr;
       if (mode_->selected_index() != kFakeModeless)
         parent = container()->GetWidget()->GetNativeView();
 
       DialogDelegate::CreateDialogWidget(
           dialog, container()->GetWidget()->GetNativeWindow(), parent);
+      ResizeDialog();

[Peter Kasting, 2017/02/25 06:04:07]

I'm vaguely surprised this is necessary, and doesn't happen automatically during
creation via ContentsChanged() or something.  (Haven't looked closely, maybe
this is reasonable.)

[tapted, 2017/02/27 10:04:19]

Well this was fun to trace :/. It boils down to a combination of things:
 1. RootView::Layout() is called twice during Widget::Init (once before and once
after the "initial" bounds are set)
 2. In DialogExample, RootView::Layout() eventually asks for
views::Label::GetPreferredSize()
 3. In the first call to RootView::Layout(), the RootView may have a size of 1x1
(There are cases on Linux and Mac where it's invalid to have a 0x0 window -- see
e.g.  NativeFrameView::GetWindowBoundsForClientBounds() below)
 4. This causes Label to be sized from 0x0 to 1x1 (even though its PreferredSize
is bigger)
 5. Then RootView::Layout() is called a second time. Label gets asked again what
its preferred size is and it now says 0x0: this is because
Label::GetPreferredSize() asks gfx::RenderText for "how many lines would fit in
1x1", and RenderText says zero. [If, instead, RenderText is asked "how many
lines would fit in 0x0" then it thinks the label wants layout, and so returns
the actual lines of text.]


1., 3. and 5. are all kinda bugs.

5. is a known problem Label::GetTextSize/PreferredSize has TODOs and cites
crbug.com/468494, crbug.com/467526
3. is hard to fix since it depends on OS constraints
1. looks straightforward to fix, and probably gains us a performance boost by
not doing 2 Layouts during Widget::Init


-> split this out to https://codereview.chromium.org/2712383002  and removed the
`ResizeDialog()` call here.

     }
     last_dialog_->GetWidget()->Show();
     return;
   }
 
   if (sender == bubble_) {
     if (bubble_->checked() && GetModalType() != ui::MODAL_TYPE_CHILD) {
       mode_->SetSelectedIndex(ui::MODAL_TYPE_CHILD);
       PrintStatus("You nearly always want Child Modal for bubbles.");
     }
@@ skipping 41 matching lines @@
 #endif
   show_->SetEnabled(enable);
   if (!enable && GetModalType() == ui::MODAL_TYPE_CHILD)
     PrintStatus("MODAL_TYPE_CHILD can't be used with non-bubbles.");
   if (!enable && GetModalType() == ui::MODAL_TYPE_SYSTEM)
     PrintStatus("MODAL_TYPE_SYSTEM isn't supported on Mac.");
 }
 
 }  // namespace examples
 }  // namespace views