views: implement width snapping for DialogDelegateViews

ui/views/bubble/tray_bubble_view.h

Index: ui/views/bubble/tray_bubble_view.h
diff --git a/ui/views/bubble/tray_bubble_view.h b/ui/views/bubble/tray_bubble_view.h
index 8de9c3053ed8a920002c80f5dd90987bff1ae8f3..86bfff4e59e96fed7557ba6c444649120abe8983 100644
--- a/ui/views/bubble/tray_bubble_view.h
+++ b/ui/views/bubble/tray_bubble_view.h
@@ -131,8 +131,10 @@ class VIEWS_EXPORT TrayBubbleView : public views::BubbleDialogDelegateView,
   void OnBeforeBubbleWidgetInit(Widget::InitParams* params,
                                 Widget* bubble_widget) const override;
 
+  // Overridden from views::DialogDelegateView.

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

Nit: Combine this and below list into the one above

+  gfx::Size GetUnsnappedPreferredSize() const override;
+
   // Overridden from views::View.
-  gfx::Size GetPreferredSize() const override;
   gfx::Size GetMaximumSize() const override;
   int GetHeightForWidth(int width) const override;
   void OnMouseEntered(const ui::MouseEvent& event) override;