Cleanup: Remove unneeded android extensions code in chrome/browser/ui.

chrome/browser/ui/android/extensions/extension_install_dialog_android.cc

-// Copyright (c) 2012 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 "base/bind.h"
-#include "chrome/browser/extensions/extension_install_prompt.h"
-
-namespace {
-
-void ShowExtensionInstallDialogImpl(
-    const ExtensionInstallPrompt::ShowParams& show_params,
-    ExtensionInstallPrompt::Delegate* delegate,
-    scoped_refptr<ExtensionInstallPrompt::Prompt> prompt) {
-  NOTIMPLEMENTED();
-}
-
-}  // namespace
-
-// static
-ExtensionInstallPrompt::ShowDialogCallback
-ExtensionInstallPrompt::GetDefaultShowDialogCallback() {
-  return base::Bind(&ShowExtensionInstallDialogImpl);
-}