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

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 43 matching lines @@
     // checkboxes below explanatory text/headings.
     SUBSECTION_HORIZONTAL_INDENT,
     // Horizontal spacing between controls that are logically unrelated.
     UNRELATED_CONTROL_HORIZONTAL_SPACING,
     // Larger horizontal spacing between unrelated controls.
     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 {
     SMALL,
     MEDIUM,
     LARGE,
   };
 
   LayoutDelegate() {}
   virtual ~LayoutDelegate() {}
@@ skipping 36 matching lines @@
 
   // 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_