Remove some more LabelButton::STYLE_BUTTON references.

ash/shell/lock_view.cc

Index: ash/shell/lock_view.cc
diff --git a/ash/shell/lock_view.cc b/ash/shell/lock_view.cc
index 7de70a40cebc77e7c7572208487f517ec758caf9..7241e4b70403cb41504bb1b2d23f14e8749d9e20 100644
--- a/ash/shell/lock_view.cc
+++ b/ash/shell/lock_view.cc
@@ -14,7 +14,7 @@
 #include "ui/gfx/font_list.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/text_utils.h"
-#include "ui/views/controls/button/label_button.h"
+#include "ui/views/controls/button/md_text_button.h"
 #include "ui/views/corewm/tooltip_controller.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/widget/widget_delegate.h"
@@ -27,8 +27,8 @@ class LockView : public views::WidgetDelegateView,
  public:
   LockView()
       : unlock_button_(
-            new views::LabelButton(this, base::ASCIIToUTF16("Unlock"))) {
-    unlock_button_->SetStyle(views::Button::STYLE_BUTTON);
+            views::MdTextButton::CreateMdButton(this,
+                                                base::ASCIIToUTF16("Unlock"))) {
     AddChildView(unlock_button_);
   }
   ~LockView() override {}
@@ -73,7 +73,7 @@ class LockView : public views::WidgetDelegateView,
   }
 
   gfx::FontList font_list_;
-  views::LabelButton* unlock_button_;
+  views::Button* unlock_button_;
 
   DISALLOW_COPY_AND_ASSIGN(LockView);
 };