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

chrome/browser/ui/views/harmony/chrome_typography.cc

Index: chrome/browser/ui/views/harmony/chrome_typography.cc
diff --git a/chrome/browser/ui/views/harmony/chrome_typography.cc b/chrome/browser/ui/views/harmony/chrome_typography.cc
index f128f7c969f0c934839eb435b916725d789ef192..93be56a7a39c7586a678bc8a16bc105556f4e3be 100644
--- a/chrome/browser/ui/views/harmony/chrome_typography.cc
+++ b/chrome/browser/ui/views/harmony/chrome_typography.cc
@@ -16,6 +16,10 @@ const gfx::FontList& LegacyTypographyProvider::GetFont(int text_context,
   gfx::Font::Weight font_weight;
   GetDefaultFont(text_context, text_style, &size_delta, &font_weight);
 
+#if defined(USE_ASH)
+  ash::GetDefaultAshFont(text_context, text_style, &size_delta, &font_weight);
+#endif
+
   switch (text_context) {
     case CONTEXT_HEADLINE:
       size_delta = kHeadlineDelta;