MacViews: add extension install dialog to MacViewsWebUIDialogs

chrome/browser/ui/views/extensions/extension_install_dialog_view.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 "chrome/browser/ui/views/extensions/extension_install_dialog_view.h"
 
 #include <stddef.h>
 #include <algorithm>
 #include <string>
 #include <utility>
@@ skipping 753 matching lines @@
     slide_animation_.Show();
 }
 
 void ExpandableContainerView::UpdateArrowToggle(bool expanded) {
   gfx::ImageSkia icon = gfx::CreateVectorIcon(
       expanded ? gfx::VectorIconId::FIND_PREV : gfx::VectorIconId::FIND_NEXT,
       16, gfx::kChromeIconGrey);
   arrow_toggle_->SetImage(views::Button::STATE_NORMAL, &icon);
 }
 
+// On Mac, GetViewsShowDialogCallback is defined in Cocoa code.
+#if !defined(OS_MACOSX)
 // static
 ExtensionInstallPrompt::ShowDialogCallback
 ExtensionInstallPrompt::GetDefaultShowDialogCallback() {
   return base::Bind(&ShowExtensionInstallDialogImpl);
 }
+#endif
+
+#if defined(OS_MACOSX)
+// static
+ExtensionInstallPrompt::ShowDialogCallback
+ExtensionInstallPrompt::GetViewsShowDialogCallback() {
+  return base::Bind(&ShowExtensionInstallDialogImpl);
+}
+#endif