MacViews: add extension install dialog to MacViewsWebUIDialogs

chrome/browser/ui/cocoa/extensions/extension_install_dialog_controller.mm

Index: chrome/browser/ui/cocoa/extensions/extension_install_dialog_controller.mm
diff --git a/chrome/browser/ui/cocoa/extensions/extension_install_dialog_controller.mm b/chrome/browser/ui/cocoa/extensions/extension_install_dialog_controller.mm
index e36188d3643d551010ff3c71b2f1f108e7a0bed1..48bfd5430826e1b2e1b90c4587780c700bbdaf64 100644
--- a/chrome/browser/ui/cocoa/extensions/extension_install_dialog_controller.mm
+++ b/chrome/browser/ui/cocoa/extensions/extension_install_dialog_controller.mm
@@ -14,6 +14,7 @@
 #include "chrome/browser/extensions/api/experience_sampling_private/experience_sampling.h"
 #include "chrome/browser/extensions/extension_install_prompt_show_params.h"
 #include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_dialogs.h"
 #include "chrome/browser/ui/browser_finder.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.h"
 #include "chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_window.h"
@@ -112,5 +113,7 @@ void ExtensionInstallDialogController::OnPromptButtonClicked(
 // static
 ExtensionInstallPrompt::ShowDialogCallback
 ExtensionInstallPrompt::GetDefaultShowDialogCallback() {
+  if (chrome::ToolkitViewsWebUIDialogsEnabled())
+    return ExtensionInstallPrompt::GetViewsShowDialogCallback();
   return base::Bind(&ShowExtensionInstallDialogImpl);
 }