Declares GetHeightForWidth() for those who need it.

ash/system/tray/special_popup_row.cc

Index: ash/system/tray/special_popup_row.cc
diff --git a/ash/system/tray/special_popup_row.cc b/ash/system/tray/special_popup_row.cc
index 40fe72dc2cfd014f00e7bd39eb1c5f65942bf856..896d1516df91739a4aec09864dd168a4b0d60b69 100644
--- a/ash/system/tray/special_popup_row.cc
+++ b/ash/system/tray/special_popup_row.cc
@@ -103,6 +103,10 @@ gfx::Size SpecialPopupRow::GetPreferredSize() {
   return size;
 }
 
+int SpecialPopupRow::GetHeightForWidth(int width) {
+  return kSpecialPopupRowHeight;
+}
+
 void SpecialPopupRow::Layout() {
   views::View::Layout();
   gfx::Rect content_bounds = GetContentsBounds();