Parametrize some more constants that will be changing in MD.

chrome/browser/ui/views/layout_constants.h

 // Copyright 2015 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_LAYOUT_CONSTANTS_H_
 #define CHROME_BROWSER_UI_VIEWS_LAYOUT_CONSTANTS_H_
 
 #include "ui/gfx/geometry/insets.h"
 
 enum LayoutConstant {
@@ skipping 15 matching lines @@
   // assets.
   LOCATION_BAR_HEIGHT,
 
   // Space between items in the location bar, as well as between items and the
   // edges.
   LOCATION_BAR_HORIZONTAL_PADDING,
 
   // The vertical padding of items in the location bar.
   LOCATION_BAR_VERTICAL_PADDING,
 
+  // The width of the New Tab button.
+  NEW_TAB_BUTTON_WIDTH,
+
   // The number of pixels in the omnibox dropdown border image interior to
   // the actual border.
   OMNIBOX_DROPDOWN_BORDER_INTERIOR,
 
   // The font size to use in the location bar and omnibox dropdown, in pixels.
   OMNIBOX_FONT_PIXEL_SIZE,
 
+  // The amount of overlap between the last tab and the new tab button.
+  TABSTRIP_NEW_TAB_BUTTON_OVERLAP,
+
   // The amount of overlap between two adjacent tabs.
   TABSTRIP_TAB_OVERLAP,
 
   // The vertical overlap of the tabstrip atop the toolbar.
   TABSTRIP_TOOLBAR_OVERLAP,
 
   // The amount by which the tab close button should overlap the trailing
   // padding region after the tab's contents region.
   TAB_CLOSE_BUTTON_TRAILING_PADDING_OVERLAP,
 
@@ skipping 44 matching lines @@
   TOOLBAR,
 
   // The spacing between a ToolbarButton's image and its border.
   TOOLBAR_BUTTON,
 };
 
 int GetLayoutConstant(LayoutConstant constant);
 gfx::Insets GetLayoutInsets(LayoutInset inset);
 
 #endif  // CHROME_BROWSER_UI_VIEWS_LAYOUT_CONSTANTS_H_