Replace network combobox with network dropdown button

chrome/browser/chromeos/login/network_screen_delegate.h

Index: chrome/browser/chromeos/login/network_screen_delegate.h
diff --git a/chrome/browser/chromeos/login/network_screen_delegate.h b/chrome/browser/chromeos/login/network_screen_delegate.h
index 6a5daf925138286df5577237f7657ef65430db78..59824d39ffbae06659166e7bb9716aba77145375 100644
--- a/chrome/browser/chromeos/login/network_screen_delegate.h
+++ b/chrome/browser/chromeos/login/network_screen_delegate.h
@@ -16,9 +16,7 @@ namespace chromeos {
 class LanguageSwitchMenu;
 
 // Interface that NetworkScreen exposes to the NetworkSelectionView.
-class NetworkScreenDelegate : public ComboboxModel,
-                              public views::Combobox::Listener,
-                              public views::ButtonListener,
+class NetworkScreenDelegate : public views::ButtonListener,
                               public NetworkLibrary::Observer {
  public:
   virtual LanguageSwitchMenu* language_switch_menu() = 0;