Declares GetHeightForWidth() for those who need it.

ash/system/tray/tray_item_view.cc

Index: ash/system/tray/tray_item_view.cc
diff --git a/ash/system/tray/tray_item_view.cc b/ash/system/tray/tray_item_view.cc
index 426ff52c3756c2ac2fb6d285b0697ca75acdfbb5..835e55e92256d0f6ab08168d6cef07ef934d7080 100644
--- a/ash/system/tray/tray_item_view.cc
+++ b/ash/system/tray/tray_item_view.cc
@@ -90,6 +90,10 @@ gfx::Size TrayItemView::GetPreferredSize() {
   return size;
 }
 
+int TrayItemView::GetHeightForWidth(int width) {
+  return GetPreferredSize().height();
+}
+
 void TrayItemView::ChildPreferredSizeChanged(views::View* child) {
   PreferredSizeChanged();
 }