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

ash/public/cpp/BUILD.gn

 # 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.
 
 # C++ headers and sources that can be used outside ash.
 component("ash_public_cpp") {
   sources = [
     "ash_public_export.h",
+    "ash_typography.cc",
+    "ash_typography.h",
     "config.h",
     "mus_property_mirror_ash.cc",
     "mus_property_mirror_ash.h",
     "session_types.h",
     "shelf_item.cc",
     "shelf_item.h",
     "shelf_item_delegate.cc",
     "shelf_item_delegate.h",
     "shelf_types.cc",
     "shelf_types.h",
     "shell_window_ids.cc",
     "shell_window_ids.h",
     "window_pin_type.cc",
     "window_pin_type.h",
     "window_properties.cc",
     "window_properties.h",
     "window_style.cc",
     "window_style.h",
   ]
 
   defines = [ "ASH_PUBLIC_IMPLEMENTATION" ]
 
   deps = [
     "//mojo/common:common_custom_types",
     "//skia/public/interfaces",
     "//ui/aura",
+    "//ui/views",
     "//ui/views/mus",
   ]
 
   public_deps = [
     "//ash/public/interfaces:interfaces_internal",
     "//base",
     "//ui/gfx",
   ]
 
   allow_circular_includes_from =
       [ "//ash/public/interfaces:interfaces_internal" ]
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "shelf_struct_traits_unittest.cc",
   ]
 
   deps = [
     ":ash_public_cpp",
     "//base",
     "//testing/gtest",
     "//ui/gfx:test_support",
   ]
 }