Removed unneeded includes of base/time.h.

net/base/tcp_pinger.h

Index: net/base/tcp_pinger.h
===================================================================
--- net/base/tcp_pinger.h	(revision 11750)
+++ net/base/tcp_pinger.h	(working copy)
@@ -10,13 +10,16 @@
 #include "base/scoped_ptr.h"
 #include "base/task.h"
 #include "base/thread.h"
-#include "base/time.h"
 #include "base/waitable_event.h"
 #include "net/base/address_list.h"
 #include "net/base/completion_callback.h"
 #include "net/base/net_errors.h"
 #include "net/base/tcp_client_socket.h"
 
+namespace base {
+  class TimeDelta;
+}
+
 namespace net {
 
 // Simple class to wait until a TCP server is accepting connections.