Improve the UI for disabling off-store extension install.

chrome/browser/download/download_crx_util.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.
 //
 // Download code which handles CRX files (extensions, themes, apps, ...).
 
 #ifndef CHROME_BROWSER_DOWNLOAD_DOWNLOAD_CRX_UTIL_H_
 #define CHROME_BROWSER_DOWNLOAD_DOWNLOAD_CRX_UTIL_H_
 
 #pragma once
@@ skipping 19 matching lines @@
 void SetMockInstallUIForTesting(ExtensionInstallUI* mock_ui);
 
 // Start installing a downloaded item item as a CRX (extension, theme, app,
 // ...).  The installer does work on the file thread, so the installation
 // is not complete when this function returns.  Returns the object managing
 // the installation.
 scoped_refptr<CrxInstaller> OpenChromeExtension(
     Profile* profile,
     const content::DownloadItem& download_item);
 
+// Returns true if this is an extension download. This also considers user
+// scripts to be extension downloads, since we convert those automatically.
+bool IsExtensionDownload(const content::DownloadItem& download_item);
+
 }  // namespace download_crx_util
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_CRX_UTIL_H_