Make all text buttons on download shelf work well with themes, not just the "show all" button.

ui/views/controls/button/md_text_button.cc

Index: ui/views/controls/button/md_text_button.cc
diff --git a/ui/views/controls/button/md_text_button.cc b/ui/views/controls/button/md_text_button.cc
index 9b3d05986a6469e9d7ec436c6575f13065149d8d..70492dca43288c6ba5f2244b317e7384b6cd162e 100644
--- a/ui/views/controls/button/md_text_button.cc
+++ b/ui/views/controls/button/md_text_button.cc
@@ -78,6 +78,8 @@ MdTextButton* MdTextButton::Create(ButtonListener* listener,
   return button;
 }
 
+MdTextButton::~MdTextButton() {}
+
 void MdTextButton::SetProminent(bool is_prominent) {
   if (is_prominent_ == is_prominent)
     return;
@@ -198,8 +200,6 @@ MdTextButton::MdTextButton(ButtonListener* listener)
   layer()->SetFillsBoundsOpaquely(false);
 }
 
-MdTextButton::~MdTextButton() {}
-
 void MdTextButton::UpdatePadding() {
   // Don't use font-based padding when there's no text visible.
   if (GetText().empty()) {