Fix the appearance of Views BlueButtons with GTK theming.

ui/views/controls/button/blue_button.cc

Index: ui/views/controls/button/blue_button.cc
diff --git a/ui/views/controls/button/blue_button.cc b/ui/views/controls/button/blue_button.cc
index ddf7e37b99e3371f4530c72edfdf3fbe245d1ea5..7189177841012a337835a61bba74f8de75cb96d4 100644
--- a/ui/views/controls/button/blue_button.cc
+++ b/ui/views/controls/button/blue_button.cc
@@ -26,7 +26,8 @@ BlueButton::BlueButton(ButtonListener* listener, const base::string16& text)
     : LabelButton(listener, text) {
   // Inherit STYLE_BUTTON insets, minimum size, alignment, etc.
   SetStyle(STYLE_BUTTON);
-  UpdateThemedBorder();
+  // Set the border explicitly, to avoid LinuxUI border theming.
+  SetBorder(CreateDefaultBorder().PassAs<Border>());
 }
 
 BlueButton::~BlueButton() {}