views: implement dialog width snapping

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 100 matching lines @@
   // Returns true if this particular dialog should use a Chrome-styled frame
   // like the one used for bubbles. The alternative is a more platform-native
   // frame.
   virtual bool ShouldUseCustomFrame() const;
 
   // A helper for accessing the DialogClientView object contained by this
   // delegate's Window.
   const DialogClientView* GetDialogClientView() const;
   DialogClientView* GetDialogClientView();
 
+  // Returns true if this dialog should have its width snapped. The default
+  // implementation always returns true.
+  virtual bool ShouldSnapFrameWidth() const;
+
  protected:
   // Overridden from WidgetDelegate:
   ui::AXRole GetAccessibleWindowRole() const override;
 
  private:
   // A flag indicating whether this dialog is able to use the custom frame
   // style for dialogs.
   bool supports_custom_frame_;
 };
 
@@ skipping 18 matching lines @@
   void ViewHierarchyChanged(
       const ViewHierarchyChangedDetails& details) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DialogDelegateView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WINDOW_DIALOG_DELEGATE_H_