Ensure that the WebstoreInstaller is always deleted on the UI thread

chrome/browser/extensions/webstore_installer.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_WEBSTORE_INSTALLER_H_
 #define CHROME_BROWSER_EXTENSIONS_WEBSTORE_INSTALLER_H_
 
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/values.h"
+#include "content/public/browser/browser_thread.h"
 #include "content/public/browser/download_id.h"
 #include "content/public/browser/download_item.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "net/base/net_errors.h"
 #include "googleurl/src/gurl.h"
 
 class FilePath;
 class Profile;
 
 namespace content {
 class NavigationController;
 }
 
 namespace extensions {
 
 // Downloads and installs extensions from the web store.
-class WebstoreInstaller : public content::NotificationObserver,
-                          public content::DownloadItem::Observer,
-                          public base::RefCounted<WebstoreInstaller> {
+class WebstoreInstaller :public content::NotificationObserver,

[miket_OOO, 2012/08/02 15:53:55]

I liked the old whitespace better.

+                         public content::DownloadItem::Observer,
+                         public base::RefCountedThreadSafe<
+  WebstoreInstaller, content::BrowserThread::DeleteOnUIThread> {
  public:
   enum Flag {
     FLAG_NONE = 0,
 
     // Inline installs trigger slightly different behavior (install source
     // is different, download referrers are the item's page in the gallery).
     FLAG_INLINE_INSTALL = 1 << 0
   };
 
   class Delegate {
@@ skipping 73 matching lines @@
   // content::NotificationObserver
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
   // Instead of using the default download directory, use |directory| instead.
   // This does *not* transfer ownership of |directory|.
   static void SetDownloadDirectoryForTests(FilePath* directory);
 
  private:
-  friend class base::RefCounted<WebstoreInstaller>;
+  friend struct content::BrowserThread::DeleteOnThread<
+   content::BrowserThread::UI>;
+  friend class base::DeleteHelper<WebstoreInstaller>;
   virtual ~WebstoreInstaller();
 
   // DownloadManager::DownloadUrl callback.
   void OnDownloadStarted(content::DownloadId id, net::Error error);
 
   // DownloadItem::Observer implementation:
   virtual void OnDownloadUpdated(content::DownloadItem* download) OVERRIDE;
   virtual void OnDownloadOpened(content::DownloadItem* download) OVERRIDE;
 
   // Starts downloading the extension to |file_path|.
@@ skipping 18 matching lines @@
   // transitions to state REMOVING.
   content::DownloadItem* download_item_;
   int flags_;
   scoped_ptr<Approval> approval_;
   GURL download_url_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_WEBSTORE_INSTALLER_H_