Default constructor for file

webrtc/base/file.cc

Index: webrtc/base/file.cc
diff --git a/webrtc/base/file.cc b/webrtc/base/file.cc
index c97504f9c737a438c1b2bd585e58bddb087810ed..b40c9732706b5535b0c975f38c327f4b6137d34a 100644
--- a/webrtc/base/file.cc
+++ b/webrtc/base/file.cc
@@ -18,6 +18,8 @@ File::~File() {
   Close();
 }
 
+File::File() : file_(kInvalidPlatformFileValue) {}
+
 File File::Open(const std::string& path) {
   return File(OpenPlatformFile(path));
 }