Enable "Hide Extension" option when "Save Link As" on the Mac

content/browser/download/download_file.h

Index: content/browser/download/download_file.h
diff --git a/content/browser/download/download_file.h b/content/browser/download/download_file.h
index 568e7ee091c27c1a610ce8041e85d4641b65bf0d..d9f2d355581de6d98af8588ef6fb78cb8dfa9dac 100644
--- a/content/browser/download/download_file.h
+++ b/content/browser/download/download_file.h
@@ -78,6 +78,9 @@ class CONTENT_EXPORT DownloadFile {
   // before RenameAndAnnotate() to take effect.
   virtual void SetClientGuid(const std::string& guid) = 0;
 
+  // Set the download file's extension's visibility in the Finder (Mac).
+  virtual void SetHideFileExtension(bool hide_extension) = 0;
+
   // For testing.  Must be called on FILE thread.
   // TODO(rdsmith): Replace use of EnsureNoPendingDownloads()
   // on the DownloadManager with a test-specific DownloadFileFactory