Enable download page action for error page

components/error_page/renderer/net_error_helper_core.h

Index: components/error_page/renderer/net_error_helper_core.h
diff --git a/components/error_page/renderer/net_error_helper_core.h b/components/error_page/renderer/net_error_helper_core.h
index d202e34f8dcac1249a272d63e5b88622be871430..e663add06c56793b5d9cc4b2720a825377484d79 100644
--- a/components/error_page/renderer/net_error_helper_core.h
+++ b/components/error_page/renderer/net_error_helper_core.h
@@ -110,6 +110,9 @@ class NetErrorHelperCore {
     // Schedule to download the page at a later time.
     virtual void DownloadPageLater() = 0;
 
+    // inform that download button is being shown in the error page.
+    virtual void SetIsShowingDownloadButton(bool show) = 0;
+
    protected:
     virtual ~Delegate() {}
   };