views: implement width snapping for DialogDelegateViews

ui/views/window/dialog_delegate.cc

Index: ui/views/window/dialog_delegate.cc
diff --git a/ui/views/window/dialog_delegate.cc b/ui/views/window/dialog_delegate.cc
index 9122b1033bb867694c0a3ae7ed03c7cd9fc450ca..b7eb6019ed5739c9b58bfabba53097e86ce501c4 100644
--- a/ui/views/window/dialog_delegate.cc
+++ b/ui/views/window/dialog_delegate.cc
@@ -241,6 +241,10 @@ DialogDelegateView::DialogDelegateView() {
 
 DialogDelegateView::~DialogDelegateView() {}
 
+gfx::Size DialogDelegateView::GetUnsnappedPreferredSize() const {
+  return View::GetPreferredSize();
+}
+
 void DialogDelegateView::DeleteDelegate() {
   delete this;
 }
@@ -262,6 +266,13 @@ void DialogDelegateView::GetAccessibleNodeData(ui::AXNodeData* node_data) {
   node_data->role = ui::AX_ROLE_DIALOG;
 }
 
+gfx::Size DialogDelegateView::GetPreferredSize() const {
+  gfx::Size size = GetUnsnappedPreferredSize();
+  size.set_width(
+      ViewsDelegate::GetInstance()->GetSnappedDialogWidth(size.width()));
+  return size;
+}
+
 void DialogDelegateView::ViewHierarchyChanged(
     const ViewHierarchyChangedDetails& details) {
   if (details.is_add && details.child == this && GetWidget())