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

ui/views/style/typography_provider.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_PROVIDER_H_
 #define UI_VIEWS_STYLE_TYPOGRAPHY_PROVIDER_H_
 
 #include "base/macros.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/font.h"
@@ skipping 13 matching lines @@
   // Gets the FontList for the given |context| and |style|.
   virtual const gfx::FontList& GetFont(int context, int style) const = 0;
 
   // Gets the color for the given |context| and |style|. This may consult
   // ui::NativeTheme.
   virtual SkColor GetColor(int context, int style) const = 0;
 
   // Gets the line spacing, or 0 if it should be provided by gfx::FontList.
   virtual int GetLineHeight(int context, int style) const = 0;
 
+  // The system may indicate a "bold" UI font is preferred (e.g. by selecting
+  // the "Bold" checkbox in Windows under "Change only the text size" in
+  // Control Panel). In this case, a user's gfx::Weight::NORMAL font will
+  // already be bold, and requesting a MEDIUM font will result in a font that is
+  // less bold. So this method returns NORMAL, if the NORMAL font is at least as
+  // bold as |weight|.
+  static gfx::Font::Weight WeightNotLighterThanNormal(gfx::Font::Weight weight);
+
  protected:
   TypographyProvider() = default;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TypographyProvider);
 };
 
 // The default provider aims to provide values to match pre-Harmony constants
 // for the given contexts so that old UI does not change.
 class VIEWS_EXPORT DefaultTypographyProvider : public TypographyProvider {
  public:
   DefaultTypographyProvider() = default;
 
   // TypographyProvider:
   const gfx::FontList& GetFont(int context, int style) const override;
   SkColor GetColor(int context, int style) const override;
   int GetLineHeight(int context, int style) const override;
 
   // Sets the |size_delta| and |font_weight| that the the default GetFont()
   // implementation uses. Always sets values, even for styles it doesn't know
   // about.
-  void GetDefaultFont(int context,
-                      int style,
-                      int* size_delta,
-                      gfx::Font::Weight* font_weight) const;
+  static void GetDefaultFont(int context,
+                             int style,
+                             int* size_delta,
+                             gfx::Font::Weight* font_weight);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DefaultTypographyProvider);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_STYLE_TYPOGRAPHY_PROVIDER_H_