views: implement dialog width snapping

chrome/browser/ui/views/harmony/layout_delegate.h

 // Copyright 2016 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 CHROME_BROWSER_UI_VIEWS_HARMONY_LAYOUT_DELEGATE_H_
 #define CHROME_BROWSER_UI_VIEWS_HARMONY_LAYOUT_DELEGATE_H_
 
 #include "ui/views/layout/grid_layout.h"
 
 namespace views {
@@ skipping 48 matching lines @@
     UNRELATED_CONTROL_HORIZONTAL_SPACING_LARGE,
     // Vertical spacing between controls that are logically unrelated.
     UNRELATED_CONTROL_VERTICAL_SPACING,
     // Larger vertical spacing between unrelated controls.
     UNRELATED_CONTROL_VERTICAL_SPACING_LARGE,
     // Padding to add to vector image buttons to increase their click and touch
     // target size.
     VECTOR_IMAGE_BUTTON_PADDING,
   };
 
   enum class DialogWidth {

[Peter Kasting, 2017/04/06 07:37:50]

This enum should disappear.

     SMALL,
     MEDIUM,
     LARGE,
   };
 
   LayoutDelegate() {}
   virtual ~LayoutDelegate() {}
 
   // Returns the active LayoutDelegate singleton, depending on UI configuration.
   // This may be an instance of this class or a subclass, e.g. a
@@ skipping 20 matching lines @@
   virtual bool ShouldShowWindowIcon() const;
 
   // DEPRECATED.  Returns whether Harmony mode is enabled.
   //
   // Instead of using this, create a generic solution that works for all UI
   // types, e.g. by adding a new LayoutDistance value that means what you need.
   //
   // TODO(pkasting): Fix callers and remove this.
   virtual bool IsHarmonyMode() const;
 
-  // Returns the preferred width in DIPs for a dialog of the specified |width|.
-  // May return 0 if the dialog has no preferred width.
-  virtual int GetDialogPreferredWidth(DialogWidth width) const;
+  // Returns the preferred width in DIPs for a dialog of the specified
+  // |min_width|. May return 0 if the dialog has no preferred width.

[Peter Kasting, 2017/04/06 06:32:16]

Nit: Comment seems outdated.  Maybe "Returns the actual width to use for a
dialog that requires at least |min_width|.  This may be used to e.g. round up to
a set of fixed widths."

+  virtual int GetSnappedDialogWidth(int min_width) const;
 
   // Returns the class that maps views::style values (TextContext and TextStyle)
   // to specific font properties (e.g. typeface, size, color, line spacing).
   virtual const views::TypographyProvider& GetTypographyProvider() const;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayoutDelegate);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_HARMONY_LAYOUT_DELEGATE_H_