Use views::style for buttons, bootstrap ash_typography to do so.

ui/views/style/typography.h

 // Copyright 2017 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_STYLE_TYPOGRAPHY_H_
 #define UI_VIEWS_STYLE_TYPOGRAPHY_H_
 
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/views/views_export.h"
 
 namespace gfx {
 class FontList;
 }
 
 namespace views {
 namespace style {
 
 // Where a piece of text appears in the UI. This influences size and weight, but
 // typically not style or color.
 enum TextContext {
   // Embedders can extend this enum with additional values that are understood
   // by the TypographyProvider offered by their ViewsDelegate. Embedders define
   // enum values from VIEWS_TEXT_CONTEXT_END. Values named beginning with
   // "CONTEXT_" represent the actual TextContexts: the rest are markers.
   VIEWS_TEXT_CONTEXT_START = 0,
 
+  // Text that appears on a button control. Usually 12pt. This includes controls
+  // with button-like behavior, such as Checkbox.
+  CONTEXT_BUTTON = VIEWS_TEXT_CONTEXT_START,
+
+  // Text that appears on an MD-styled dialog button control. Usually 12pt.
+  CONTEXT_BUTTON_MD,
+
   // A title for a dialog window. Usually 15pt. Multi-line OK.
-  CONTEXT_DIALOG_TITLE = VIEWS_TEXT_CONTEXT_START,
+  CONTEXT_DIALOG_TITLE,
 
   // Text to label a control, usually next to it. "Body 2". Usually 12pt.
   CONTEXT_LABEL,
 
   // An editable text field. Usually matches CONTROL_LABEL.
   CONTEXT_TEXTFIELD,
 
-  // Text that appears on a button control. Usually 12pt.
-  CONTEXT_BUTTON,
+  // Text for the menu items that appear in the touch-selection context menu.
+  CONTEXT_TOUCH_MENU,
 
   // Embedders must start TextContext enum values from this value.
   VIEWS_TEXT_CONTEXT_END,
 
   // All TextContext enum values must be below this value.
   TEXT_CONTEXT_MAX = 0x1000
 };
 
 // How a piece of text should be presented. This influences color and style, but
 // typically not size.
 enum TextStyle {
   // TextStyle enum values must always be greater than any TextContext value.
   // This allows the code to verify at runtime that arguments of the two types
   // have not been swapped.
   VIEWS_TEXT_STYLE_START = TEXT_CONTEXT_MAX,
 
   // Primary text: solid black, normal weight. Converts to DISABLED in some
   // contexts (e.g. BUTTON_TEXT, FIELD).
   STYLE_PRIMARY = VIEWS_TEXT_STYLE_START,
 
+  // Style for the default button on a dialog.
+  STYLE_DIALOG_BUTTON_DEFAULT,
+
   // Disabled "greyed out" text.
   STYLE_DISABLED,
 
   // The style used for links. Usually a solid shade of blue.
   STYLE_LINK,
 
   // Active tab in a tabbed pane.
   STYLE_TAB_ACTIVE,
 
   // Hovered tab in a tabbed pane.
@@ skipping 11 matching lines @@
 // value understood by the embedder's TypographyProvider. Similarly,
 // |text_style| corresponds to TextStyle.
 VIEWS_EXPORT const gfx::FontList& GetFont(int text_context, int text_style);
 VIEWS_EXPORT SkColor GetColor(int text_context, int text_style);
 VIEWS_EXPORT int GetLineHeight(int text_context, int text_style);
 
 }  // namespace style
 }  // namespace views
 
 #endif  // UI_VIEWS_STYLE_TYPOGRAPHY_H_