views: implement dialog width snapping

ui/views/window/dialog_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 "ui/views/window/dialog_delegate.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "build/build_config.h"
@@ skipping 209 matching lines @@
 }
 
 const DialogClientView* DialogDelegate::GetDialogClientView() const {
   return GetWidget()->client_view()->AsDialogClientView();
 }
 
 DialogClientView* DialogDelegate::GetDialogClientView() {
   return GetWidget()->client_view()->AsDialogClientView();
 }
 
+bool DialogDelegate::ShouldSnapFrameWidth() const {
+  return true;

[Peter Kasting, 2017/04/06 06:32:16]

Since this patch already makes bubbles-that-aren't-dialogs not snap, do we
actually need this method?

+}
+
 ui::AXRole DialogDelegate::GetAccessibleWindowRole() const {
   return ui::AX_ROLE_DIALOG;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // DialogDelegateView:
 
 DialogDelegateView::DialogDelegateView() {
   // A WidgetDelegate should be deleted on DeleteDelegate.
   set_owned_by_client();
@@ skipping 22 matching lines @@
   node_data->role = ui::AX_ROLE_DIALOG;
 }
 
 void DialogDelegateView::ViewHierarchyChanged(
     const ViewHierarchyChangedDetails& details) {
   if (details.is_add && details.child == this && GetWidget())
     NotifyAccessibilityEvent(ui::AX_EVENT_ALERT, true);
 }
 
 }  // namespace views