Default constructor for file

webrtc/base/file.h

Index: webrtc/base/file.h
diff --git a/webrtc/base/file.h b/webrtc/base/file.h
index 6ca4825ed006dd9e72bd689bb907198b129901d6..10fb69834b1e30f33f9707bd1a7b48e3378e224e 100644
--- a/webrtc/base/file.h
+++ b/webrtc/base/file.h
@@ -30,6 +30,8 @@ class File {
   // Wraps the given PlatformFile. This class is then responsible for closing
   // the file, which will be done in the destructor if Close is never called.
   explicit File(PlatformFile);
+  // The default constructor produces a closed file.
+  File();
   ~File();
 
   File(File&& other);