Revert 179916. It breaks on Mac.

chrome/browser/ui/views/extensions/extension_install_dialog_view.cc

Index: chrome/browser/ui/views/extensions/extension_install_dialog_view.cc
===================================================================
--- chrome/browser/ui/views/extensions/extension_install_dialog_view.cc	(revision 182273)
+++ chrome/browser/ui/views/extensions/extension_install_dialog_view.cc	(working copy)
@@ -95,7 +95,6 @@
 
  private:
   // views::DialogDelegateView:
-  virtual int GetDialogButtons() const OVERRIDE;
   virtual string16 GetDialogButtonLabel(ui::DialogButton button) const OVERRIDE;
   virtual int GetDefaultDialogButton() const OVERRIDE;
   virtual bool Cancel() OVERRIDE;
@@ -444,14 +443,6 @@
   GetWidget()->SetSize(GetWidget()->non_client_view()->GetPreferredSize());
 }
 
-int ExtensionInstallDialogView::GetDialogButtons() const {
-  int buttons = prompt_.GetDialogButtons();
-  // Simply having just an OK button is *not* supported. See comment on function
-  // GetDialogButtons in dialog_delegate.h for reasons.
-  DCHECK_GT(buttons & ui::DIALOG_BUTTON_CANCEL, 0);
-  return buttons;
-}
-
 string16 ExtensionInstallDialogView::GetDialogButtonLabel(
     ui::DialogButton button) const {
   switch (button) {