Fix some string16 -> base::string16 that have crept into ui/.

ui/views/controls/label.cc

Index: ui/views/controls/label.cc
diff --git a/ui/views/controls/label.cc b/ui/views/controls/label.cc
index c61deec9206bb0e38caf28e1a9bc110ded21e307..dcd33f6b8e69da9b332ef2acdb60e3bc453d4e2d 100644
--- a/ui/views/controls/label.cc
+++ b/ui/views/controls/label.cc
@@ -233,7 +233,7 @@ gfx::Size Label::GetMinimumSize() {
   if ((!visible() && collapse_when_hidden_) || text_size.IsEmpty())
     return gfx::Size();
 
-  gfx::Size size(font_list_.GetStringWidth(string16(gfx::kEllipsisUTF16)),
+  gfx::Size size(font_list_.GetStringWidth(base::string16(gfx::kEllipsisUTF16)),
                  font_list_.GetHeight());
   size.SetToMin(text_size);  // The actual text may be shorter than an ellipsis.
   gfx::Insets insets = GetInsets();