Adding a DownloadRestrictions group policy.

chrome/browser/download/chrome_download_manager_delegate.h

Index: chrome/browser/download/chrome_download_manager_delegate.h
diff --git a/chrome/browser/download/chrome_download_manager_delegate.h b/chrome/browser/download/chrome_download_manager_delegate.h
index 5d9fd8a83220ade0db22816b6bc158445d7ebd94..2eaf5f40627f1b466475d36b904a64daf8c7c494 100644
--- a/chrome/browser/download/chrome_download_manager_delegate.h
+++ b/chrome/browser/download/chrome_download_manager_delegate.h
@@ -164,6 +164,10 @@ class ChromeDownloadManagerDelegate
   // Returns true if |path| should open in the browser.
   bool IsOpenInBrowserPreferreredForFile(const base::FilePath& path);
 
+  // Return true if the downloaded file should be blocked based on the current
+  // download restriction pref and |danger_type|.
+  bool ShouldBlockFile(content::DownloadDangerType danger_type) const;
+
   Profile* profile_;
   uint32_t next_download_id_;
   IdCallbackVector id_callbacks_;