Use GridLayout for DialogClientView's button row.

ui/views/examples/dialog_example.cc

Index: ui/views/examples/dialog_example.cc
diff --git a/ui/views/examples/dialog_example.cc b/ui/views/examples/dialog_example.cc
index 637c6dafabb1957002431d3e709998ed9e4c4af4..d9af9a4db6959db528a3e1dfb5d8e30ad97e5815 100644
--- a/ui/views/examples/dialog_example.cc
+++ b/ui/views/examples/dialog_example.cc
@@ -245,6 +245,10 @@ void DialogExample::ResizeDialog() {
   // 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) {
@@ -266,6 +270,7 @@ void DialogExample::ButtonPressed(Button* sender, const ui::Event& event) {
 
       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;