Use BookmarkAppConfirmationView on Mac. Delete the NSAlert Mac uses currently.

chrome/browser/extensions/bookmark_app_helper.h

 // Copyright 2014 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_BOOKMARK_APP_HELPER_H_
 #define CHROME_BROWSER_EXTENSIONS_BOOKMARK_APP_HELPER_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 91 matching lines @@
       std::map<int, BookmarkAppHelper::BitmapAndSource> bitmap_map,
       WebApplicationInfo* web_app_info);
 
   // Begins the asynchronous bookmark app creation.
   void Create(const CreateBookmarkAppCallback& callback);
 
   // Begins the asynchronous bookmark app creation from an app banner.
   void CreateFromAppBanner(const CreateBookmarkAppCallback& callback,
                            const content::Manifest& manifest);
 
- private:
-  friend class TestBookmarkAppHelper;
+ protected:
+  // Protected methods for testing.
 
   // Called by the WebContents when the manifest has been downloaded. If there
   // is no manifest, or the WebContents is destroyed before the manifest could
   // be downloaded, this is called with an empty manifest.
   void OnDidGetManifest(const GURL& manifest_url,
                         const content::Manifest& manifest);
 
   // Performs post icon download tasks including installing the bookmark app.
-  void OnIconsDownloaded(bool success,
-                         const std::map<GURL, std::vector<SkBitmap> >& bitmaps);
+  virtual void OnIconsDownloaded(
+      bool success,
+      const std::map<GURL, std::vector<SkBitmap>>& bitmaps);
 
+ private:
   // Called after the bubble has been shown, and the user has either accepted or
   // the dialog was dismissed.
   void OnBubbleCompleted(bool user_accepted,
                          const WebApplicationInfo& web_app_info);
 
   // Called when the installation of the app is complete to perform the final
   // installation steps.
   void FinishInstallation(const Extension* extension);
 
   // Overridden from content::NotificationObserver:
@@ skipping 41 matching lines @@
     content::BrowserContext* browser_context,
     const extensions::Extension* extension,
     const base::Callback<void(const WebApplicationInfo&)> callback);
 
 // Returns whether the given |url| is a valid bookmark app url.
 bool IsValidBookmarkAppUrl(const GURL& url);
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_BOOKMARK_APP_HELPER_H_