MacViews: add extension install dialog to MacViewsWebUIDialogs

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

Index: chrome/browser/ui/views/extensions/extension_install_dialog_view.cc
diff --git a/chrome/browser/ui/views/extensions/extension_install_dialog_view.cc b/chrome/browser/ui/views/extensions/extension_install_dialog_view.cc
index c9c9ce00cbc558f9b95b4ce06a21fcc3cd857a12..890a3cb55ab9b12fa59fedfabb19798f70cb5893 100644
--- a/chrome/browser/ui/views/extensions/extension_install_dialog_view.cc
+++ b/chrome/browser/ui/views/extensions/extension_install_dialog_view.cc
@@ -771,8 +771,19 @@ void ExpandableContainerView::UpdateArrowToggle(bool expanded) {
   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