Revert r14620 which was a rollback of r14549 and r14508. This

chrome/browser/app_modal_dialog_gtk.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/app_modal_dialog.h"
 
 #include <gtk/gtk.h>
 
 #include "base/logging.h"
 #include "base/string_util.h"
@@ skipping 89 matching lines @@
 
 void AppModalDialog::ActivateModalDialog() {
   NOTIMPLEMENTED();
 }
 
 void AppModalDialog::CloseModalDialog() {
   NOTIMPLEMENTED();
 }
 
 int AppModalDialog::GetDialogButtons() {
-  NOTIMPLEMENTED();
-  return 0;
+  switch (dialog_flags_) {
+    case MessageBoxFlags::kIsJavascriptAlert:
+      return MessageBoxFlags::DIALOGBUTTON_OK;
+
+    case MessageBoxFlags::kIsJavascriptConfirm:
+      return MessageBoxFlags::DIALOGBUTTON_OK |
+             MessageBoxFlags::DIALOGBUTTON_CANCEL;
+
+    case MessageBoxFlags::kIsJavascriptPrompt:
+      return MessageBoxFlags::DIALOGBUTTON_OK;
+
+    default:
+      NOTREACHED();
+      return 0;
+  }
 }
 
 void AppModalDialog::AcceptWindow() {
-  NOTIMPLEMENTED();
+  OnDialogResponse(GTK_DIALOG(dialog_), GTK_RESPONSE_OK, this);
 }
 
 void AppModalDialog::CancelWindow() {
-  NOTIMPLEMENTED();
+  OnDialogResponse(GTK_DIALOG(dialog_), GTK_RESPONSE_CANCEL, this);
 }