Change default timestamp to 64 bits in all webrtc directories.

webrtc/libjingle/xmpp/pingtask.h

Index: webrtc/libjingle/xmpp/pingtask.h
diff --git a/webrtc/libjingle/xmpp/pingtask.h b/webrtc/libjingle/xmpp/pingtask.h
index 22fd94d721738c5c285ea2b7ff295a1916d2ae1a..b070a1ccf1ebbc83b5c4acd9c1b7a544098300e6 100644
--- a/webrtc/libjingle/xmpp/pingtask.h
+++ b/webrtc/libjingle/xmpp/pingtask.h
@@ -46,8 +46,8 @@ class PingTask : public buzz::XmppTask, private rtc::MessageHandler {
   rtc::MessageQueue* message_queue_;
   uint32_t ping_period_millis_;
   uint32_t ping_timeout_millis_;
-  uint32_t next_ping_time_;
-  uint32_t ping_response_deadline_;  // 0 if the response has been received
+  int64_t next_ping_time_;
+  int64_t ping_response_deadline_;  // 0 if the response has been received
 };
 
 } // namespace buzz