Adding a DownloadRestrictions group policy.

content/public/browser/download_manager_delegate.cc

Index: content/public/browser/download_manager_delegate.cc
diff --git a/content/public/browser/download_manager_delegate.cc b/content/public/browser/download_manager_delegate.cc
index 9351ce227112181992a2f2d9e20d72921e5e4bba..0b9fef37bf099b3899d3dd3c7def4c1a64146c5b 100644
--- a/content/public/browser/download_manager_delegate.cc
+++ b/content/public/browser/download_manager_delegate.cc
@@ -4,6 +4,8 @@
 
 #include "content/public/browser/download_manager_delegate.h"
 
+#include <string>
+
 #include "content/public/browser/download_item.h"
 
 namespace content {
@@ -45,4 +47,8 @@ DownloadManagerDelegate::ApplicationClientIdForFileScanning() const {
 
 DownloadManagerDelegate::~DownloadManagerDelegate() {}
 
+bool DownloadManagerDelegate::ShouldBlockAllDownloads() const {
+  return false;
+}
+
 }  // namespace content