Making ShowExtensionInstallDialog a callback

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

 // 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.
 
 #import "chrome/browser/ui/cocoa/extensions/extension_install_dialog_controller.h"
 
 #include "base/auto_reset.h"
 #include "base/i18n/rtl.h"
 #include "base/mac/bundle_locations.h"
 #include "base/mac/mac_util.h"
@@ skipping 516 matching lines @@
                      isGroupItem:YES
                         children:children]];
   }
 
   return warnings;
 }
 
 
 @end  // ExtensionInstallDialogController
 
-void ShowExtensionInstallDialogImpl(
-    gfx::NativeWindow parent,
-    content::PageNavigator* navigator,
-    ExtensionInstallPrompt::Delegate* delegate,
-    const ExtensionInstallPrompt::Prompt& prompt) {
-  ExtensionInstallDialogController* controller =
-      [[ExtensionInstallDialogController alloc]
-        initWithParentWindow:parent
-                     navigator:navigator
-                    delegate:delegate
-                      prompt:prompt];
+class ExtensionInstallDialogMac : public ExtensionInstallDialog {
+ public:
+  virtual void ShowExtensionInstallDialogImpl(
+      gfx::NativeWindow parent,
+      content::PageNavigator* navigator,
+      ExtensionInstallPrompt::Delegate* delegate,
+      const ExtensionInstallPrompt::Prompt& prompt) OVERRIDE {
+    ExtensionInstallDialogController* controller =
+        [[ExtensionInstallDialogController alloc]
+          initWithParentWindow:parent
+                       navigator:navigator
+                      delegate:delegate
+                        prompt:prompt];
 
-  // TODO(mihaip): Switch this to be tab-modal (http://crbug.com/95455)
-  [controller runAsModalSheet];
+    // TODO(mihaip): Switch this to be tab-modal (http://crbug.com/95455)
+    [controller runAsModalSheet];
+  }
+
+ private:
+  ~ExtensionInstallDialogMac() {
+  }
+};
+
+// static
+scoped_refptr<ExtensionInstallDialog>
+ExtensionInstallDialog::CreateDefaultImpl() {
+  return new ExtensionInstallDialogMac;
 }