Introduce new flag to control usage of MD in secondary (not top-chrome)

ui/views/controls/button/label_button.cc

 // Copyright (c) 2012 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.
 
 #include "ui/views/controls/button/label_button.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 183 matching lines @@
 
 void LabelButton::SetIsDefault(bool is_default) {
   DCHECK_EQ(STYLE_BUTTON, style_);
   if (is_default == is_default_)
     return;
 
   is_default_ = is_default;
   ui::Accelerator accel(ui::VKEY_RETURN, ui::EF_NONE);
   is_default_ ? AddAccelerator(accel) : RemoveAccelerator(accel);
 
-  const bool bold = PlatformStyle::kDefaultLabelButtonHasBoldFont && is_default;
-  label_->SetFontList(bold ? cached_bold_font_list_ : cached_normal_font_list_);
-  InvalidateLayout();
-  ResetLabelEnabledColor();
+  UpdateStyleToIndicateDefaultStatus();
 }
 
 void LabelButton::SetStyle(ButtonStyle style) {
   // All callers currently pass STYLE_BUTTON, and should only call this once, to
   // change from the default style.
   DCHECK_EQ(style, STYLE_BUTTON);
   DCHECK_EQ(style_, STYLE_TEXTBUTTON);
   DCHECK(!GetWidget()) << "Can't change button style after adding to a Widget.";
 
   style_ = style;
@@ skipping 268 matching lines @@
   }
 
   for (size_t state = STATE_NORMAL; state < STATE_COUNT; ++state) {
     if (!explicitly_set_colors_[state]) {
       SetTextColor(static_cast<ButtonState>(state), colors[state]);
       explicitly_set_colors_[state] = false;
     }
   }
 }
 
+void LabelButton::UpdateStyleToIndicateDefaultStatus() {
+  const bool bold =
+      PlatformStyle::kDefaultLabelButtonHasBoldFont && is_default_;
+  label_->SetFontList(bold ? cached_bold_font_list_ : cached_normal_font_list_);
+  InvalidateLayout();
+  ResetLabelEnabledColor();
+}
+
 void LabelButton::UpdateImage() {
   image_->SetImage(GetImage(state()));
   ResetCachedPreferredSize();
 }
 
 void LabelButton::UpdateThemedBorder() {
   // Don't override borders set by others.
   if (!border_is_themed_border_)
     return;
 
@@ skipping 56 matching lines @@
 void LabelButton::ResetLabelEnabledColor() {
   const SkColor color =
       explicitly_set_colors_[state()]
           ? button_state_colors_[state()]
           : PlatformStyle::TextColorForButton(button_state_colors_, *this);
   if (state() != STATE_DISABLED && label_->enabled_color() != color)
     label_->SetEnabledColor(color);
 }
 
 }  // namespace views