Use an InsetMetric instead of a constant for vector button padding.

ui/views/views_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_VIEWS_DELEGATE_H_
 #define UI_VIEWS_VIEWS_DELEGATE_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 53 matching lines @@
 
 enum class InsetsMetric {
   // The margins that should be applied around a bubble dialog.
   BUBBLE_DIALOG,
   // The insets that should be applied around a DialogClientView. Note that
   // the top inset is used for the distance between the buttons and the
   // DialogClientView's content view.
   DIALOG_BUTTON,
   // The insets that should be applied around a dialog's frame view.
   DIALOG_FRAME_VIEW,
+  // Padding to add to vector image buttons to increase their click and touch
+  // target size.
+  VECTOR_IMAGE_BUTTON_PADDING,
 };
 
 enum class DistanceMetric {
   // The default padding to add on each side of a button's label.
   BUTTON_HORIZONTAL_PADDING,
   // The distance between a dialog's edge and the close button in the upper
   // trailing corner.
   CLOSE_BUTTON_MARGIN,
   // The default minimum width of a dialog button.
   DIALOG_BUTTON_MINIMUM_WIDTH,
@@ skipping 186 matching lines @@
 #endif
 
   NativeWidgetFactory native_widget_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ViewsDelegate);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_VIEWS_DELEGATE_H_