Adding a DownloadRestrictions group policy.

content/public/browser/download_item.h

Index: content/public/browser/download_item.h
diff --git a/content/public/browser/download_item.h b/content/public/browser/download_item.h
index 32963bfd476415a5b22a75857900d68b462c7527..aa89a513badda07128dad4bdd158b874e1b633f7 100644
--- a/content/public/browser/download_item.h
+++ b/content/public/browser/download_item.h
@@ -73,10 +73,10 @@ class CONTENT_EXPORT DownloadItem : public base::SupportsUserData {
 
   // How the final target path should be used.
   enum TargetDisposition {
-    TARGET_DISPOSITION_OVERWRITE, // Overwrite if the target already exists.
-    TARGET_DISPOSITION_PROMPT     // Prompt the user for the actual
-                                  // target. Implies
-                                  // TARGET_DISPOSITION_OVERWRITE.
+    TARGET_DISPOSITION_OVERWRITE,  // Overwrite if the target already exists.
+    TARGET_DISPOSITION_PROMPT      // Prompt the user for the actual
+                                   // target. Implies
+                                   // TARGET_DISPOSITION_OVERWRITE.
   };
 
   // Callback used with AcquireFileAndDeleteDownload().
@@ -394,8 +394,9 @@ class CONTENT_EXPORT DownloadItem : public base::SupportsUserData {
 
   // Called if a check of the download contents was performed and the results of
   // the test are available. This should only be called after AllDataSaved() is
-  // true.
-  virtual void OnContentCheckCompleted(DownloadDangerType danger_type) = 0;
+  // true. If |block_file| is true, then the download file should be blocked.
+  virtual void OnContentCheckCompleted(DownloadDangerType danger_type,
+                                       bool block_file) = 0;
 
   // Mark the download to be auto-opened when completed.
   virtual void SetOpenWhenComplete(bool open) = 0;