Don't allow Checkboxes to participate in equal-sized-buttons in Harmony dialogs.

ui/views/window/dialog_client_view.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 "ui/views/window/dialog_client_view.h"
 
 #include <algorithm>
 
 #include "build/build_config.h"
 #include "ui/base/material_design/material_design_controller.h"
@@ skipping 374 matching lines @@
   for (size_t view_index = 0; view_index < kNumButtons; ++view_index) {
     if (views[view_index]) {
       layout->AddView(views[view_index]);
       link[link_index++] = kViewToColumnIndex[view_index];
     } else {
       layout->SkipColumns(1);
     }
   }
 
   if (ui::MaterialDesignController::IsSecondaryUiMaterial()) {
-    // Only link the extra view column if it is a button.
-    if (views[0] && !CustomButton::AsCustomButton(views[0]))
+    // Only link the extra view column if its View type matches the buttons. And
+    // if there's only buttons or only the extra view, everything can be linked.
+    View* either_button_view = ok_button_ ? ok_button_ : cancel_button_;
+    if (either_button_view && extra_view_ &&

[msw, 2017/05/02 17:20:10]

nit: curlies for multi-line conditional?

[tapted, 2017/05/03 00:16:59]

Broke out a separate bool - condition got a little too messy.

+        either_button_view->GetClassName() != extra_view_->GetClassName())

[msw, 2017/05/02 17:20:10]

Won't this exclude other cases that we would want to be linked? (eg. ok/cancel
is a MdTextButton/BlueButton, but the extra view is a LabelButton), there are
lots of button subclasses... Maybe just exclude checkbox extra views?

[tapted, 2017/05/03 00:16:59]

Done.

I think, because this is only for Harmony, there should only be MdTextButton
(dialogs should be using MdTextButton::CreateSecondaryUi[Blue]Button which will
always be MdTextButton, possibly with SetProminent(true)). And dialogs shouldn't
mix LabelButtons and MdTextButton.

But it could be limiting in other ways, and I like the idea of just excluding
Checkbox (downside is a teeny bit of coupling between DialogClientView and
Checkbox). There is also RadioButton.. but I think we can assume nobody is going
to put that in the extra view slot.

[msw, 2017/05/03 18:21:01]

Random dialogs might be using LabelButton for the extra view.

       column_set->LinkColumnSizes(link[1], link[2], -1);
     else
       column_set->LinkColumnSizes(link[0], link[1], link[2], -1);
   }
   layout->AddPaddingRow(kFixed, insets.bottom());
 }
 
 void DialogClientView::SetupViews() {
   button_row_container_->RemoveAllChildViews(false /* delete children */);
   // If SetupLayout() "stored" a hidden |extra_view_| in |this|, ensure it can
   // be re-added to the layout when becoming visible.
   if (extra_view_)
     RemoveChildView(extra_view_);
 
   UpdateDialogButton(&ok_button_, ui::DIALOG_BUTTON_OK);
   UpdateDialogButton(&cancel_button_, ui::DIALOG_BUTTON_CANCEL);
 
   if (extra_view_)
     return;
 
   extra_view_ = GetDialogDelegate()->CreateExtraView();
   if (extra_view_)
     extra_view_->SetGroup(kButtonGroup);
 }
 
 }  // namespace views