views: support dialog width snapping once and for all

ui/views/layout/layout_provider.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/layout/layout_provider.h"
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/views/layout/layout_constants.h"
@@ skipping 56 matching lines @@
       return kButtonHorizontalPadding;
   }
   NOTREACHED();
   return 0;
 }
 
 const TypographyProvider& LayoutProvider::GetTypographyProvider() const {
   return typography_provider_;
 }
 
-}  // namespace views
+int LayoutProvider::GetSnappedDialogWidth(int min_width) const {
+  return min_width;
+}
+
+}  // namespace views