Make MdTextButton a LabelButton, use it in the DL shelf.

ui/views/controls/button/label_button.cc

Index: ui/views/controls/button/label_button.cc
diff --git a/ui/views/controls/button/label_button.cc b/ui/views/controls/button/label_button.cc
index f192e1282b258644d0a913accb63245831b2b5e4..1f023067ff0af57efa5138000c689daf5d9375bb 100644
--- a/ui/views/controls/button/label_button.cc
+++ b/ui/views/controls/button/label_button.cc
@@ -93,7 +93,7 @@ LabelButton::LabelButton(ButtonListener* listener, const base::string16& text)
       image_label_spacing_(kSpacing),
       horizontal_alignment_(gfx::ALIGN_LEFT) {
   SetAnimationDuration(kHoverAnimationDurationMs);
-  SetText(text);
+  SetTextInternal(text);
 
   AddChildView(ink_drop_container_);
   ink_drop_container_->SetPaintToLayer(true);
@@ -131,8 +131,7 @@ const base::string16& LabelButton::GetText() const {
 }
 
 void LabelButton::SetText(const base::string16& text) {
-  SetAccessibleName(text);
-  label_->SetText(text);
+  SetTextInternal(text);
 }
 
 void LabelButton::SetTextColor(ButtonState for_state, SkColor color) {
@@ -166,10 +165,7 @@ void LabelButton::SetFontList(const gfx::FontList& font_list) {
   cached_normal_font_list_ = font_list;
   cached_bold_font_list_ = font_list.DeriveWithStyle(
       font_list.GetFontStyle() | gfx::Font::BOLD);
-
-  // STYLE_BUTTON uses bold text to indicate default buttons.
-  label_->SetFontList(
-      style_ == STYLE_BUTTON && is_default_ ?
+  label_->SetFontList(is_default_ ?
       cached_bold_font_list_ : cached_normal_font_list_);
 }
 
@@ -194,18 +190,17 @@ void LabelButton::SetMaxSize(const gfx::Size& max_size) {
 }
 
 void LabelButton::SetIsDefault(bool is_default) {
+  DCHECK_EQ(STYLE_BUTTON, style_);

[Evan Stade, 2016/03/08 02:04:15]

We don't call SetIsDefault for any STYLE_TEXTBUTTON button (I think --- trybots
are confirming). I'm hoping that when we switch everything to MD we can get rid
of LabelButton::SetStyle(). Then we'll have:

button = views::MdTextButton::Create();

instead of

button = new views::LabelButton();
button->SetStyle();

with a tall stack of DCHECKs in SetStyle. SetIsDefault would move to
MdTextButton also.

   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);
 
-  // STYLE_BUTTON uses bold text to indicate default buttons.
-  if (style_ == STYLE_BUTTON) {
-    label_->SetFontList(
-        is_default ? cached_bold_font_list_ : cached_normal_font_list_);
-    InvalidateLayout();
-  }
+  label_->SetFontList(
+      is_default ? cached_bold_font_list_ : cached_normal_font_list_);
+  InvalidateLayout();
 }
 
 void LabelButton::SetStyle(ButtonStyle style) {
@@ -521,6 +516,11 @@ void LabelButton::UpdateThemedBorder() {
   border_is_themed_border_ = true;
 }
 
+void LabelButton::SetTextInternal(const base::string16& text) {
+  SetAccessibleName(text);
+  label_->SetText(text);
+}
+
 void LabelButton::ChildPreferredSizeChanged(View* child) {
   ResetCachedPreferredSize();
   PreferredSizeChanged();