Delete unused class AsyncFile.

webrtc/base/physicalsocketserver.h

Index: webrtc/base/physicalsocketserver.h
diff --git a/webrtc/base/physicalsocketserver.h b/webrtc/base/physicalsocketserver.h
index 3437eb8cb3e0392a3fa7538b81928d0856157957..462fab2b1846998e3bcf357cdb8f4c76f341c2c0 100644
--- a/webrtc/base/physicalsocketserver.h
+++ b/webrtc/base/physicalsocketserver.h
@@ -14,7 +14,6 @@
 #include <memory>
 #include <vector>
 
-#include "webrtc/base/asyncfile.h"
 #include "webrtc/base/nethelpers.h"
 #include "webrtc/base/socketserver.h"
 #include "webrtc/base/criticalsection.h"
@@ -79,8 +78,6 @@ class PhysicalSocketServer : public SocketServer {
   void Remove(Dispatcher* dispatcher);
 
 #if defined(WEBRTC_POSIX)
-  AsyncFile* CreateFile(int fd);
-
   // Sets the function to be executed in response to the specified POSIX signal.
   // The function is executed from inside Wait() using the "self-pipe trick"--
   // regardless of which thread receives the signal--and hence can safely