views: implement width snapping for DialogDelegateViews

ui/views/window/dialog_delegate.h

 // 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.
 
 #ifndef UI_VIEWS_WINDOW_DIALOG_DELEGATE_H_
 #define UI_VIEWS_WINDOW_DIALOG_DELEGATE_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/strings/string16.h"
@@ skipping 120 matching lines @@
 // A DialogDelegate implementation that is-a View. Used to override GetWidget()
 // to call View's GetWidget() for the common case where a DialogDelegate
 // implementation is-a View. Note that DialogDelegateView is not owned by
 // view's hierarchy and is expected to be deleted on DeleteDelegate call.
 class VIEWS_EXPORT DialogDelegateView : public DialogDelegate,
                                         public View {
  public:
   DialogDelegateView();
   ~DialogDelegateView() override;
 
+  virtual gfx::Size GetUnsnappedPreferredSize() const;

[Peter Kasting, 2017/03/30 00:35:36]

Nit: Comment

+
   // Overridden from DialogDelegate:
   void DeleteDelegate() override;
   Widget* GetWidget() override;
   const Widget* GetWidget() const override;
   View* GetContentsView() override;
 
   // Overridden from View:
   void GetAccessibleNodeData(ui::AXNodeData* node_data) override;
+  gfx::Size GetPreferredSize() const final;
   void ViewHierarchyChanged(
       const ViewHierarchyChangedDetails& details) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DialogDelegateView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WINDOW_DIALOG_DELEGATE_H_