Remove unused lambda capture to unbreak downstream code.

Broken since: https://chromium.googlesource.com/external/webrtc/+/d3c3a4e2ac0f42218705a48eb7bc0e507998d833

BUG=none
TBR=zhihuang@webrtc.org

Review-Url: https://codereview.webrtc.org/2639523002
Cr-Commit-Position: refs/heads/master@{#16121}
diff --git a/webrtc/p2p/base/p2ptransportchannel.cc b/webrtc/p2p/base/p2ptransportchannel.cc
index 532d35c..7819ce8 100644
--- a/webrtc/p2p/base/p2ptransportchannel.cc
+++ b/webrtc/p2p/base/p2ptransportchannel.cc
@@ -1691,7 +1691,7 @@
                [this, now](Connection* conn) { return IsPingable(conn, now); });
   auto iter =
       std::max_element(pingable_connections.begin(), pingable_connections.end(),
-                       [this, now](Connection* conn1, Connection* conn2) {
+                       [this](Connection* conn1, Connection* conn2) {
                          return MorePingable(conn1, conn2) == conn2;
                        });
   if (iter != pingable_connections.end()) {