Do not call stat() when reading directories via File API.

chrome/common/extensions/api/file_system_provider.idl

Index: chrome/common/extensions/api/file_system_provider.idl
diff --git a/chrome/common/extensions/api/file_system_provider.idl b/chrome/common/extensions/api/file_system_provider.idl
index 1eacb25faa05001b3811e267c9d158a6566ef9c3..342301bc60d5bda6c464e3bb81244c8136ffd48c 100644
--- a/chrome/common/extensions/api/file_system_provider.idl
+++ b/chrome/common/extensions/api/file_system_provider.idl
@@ -61,11 +61,12 @@ namespace fileSystemProvider {
     // it must be empty.
     DOMString name;
 
-    // File size in bytes.
-    double size;
+    // File size in bytes. Required for <code>OnGetMetadataRequested</code>.
+    double? size;
 
-    // The last modified time of this entry.
-    [instanceOf=Date] object modificationTime;
+    // The last modified time of this entry. Required for
+    // <code>OnGetMetadataRequested</code>.
+    [instanceOf=Date] object? modificationTime;
 
     // Mime type for the entry.
     DOMString? mimeType;