Close idle H2 sockets when SpdySession is initialized.

net/http/http_proxy_client_socket_pool.cc

Index: net/http/http_proxy_client_socket_pool.cc
diff --git a/net/http/http_proxy_client_socket_pool.cc b/net/http/http_proxy_client_socket_pool.cc
index b83e9249ecf949bebc205a41f21784e48de9be51..bda4e95b500e8f4df08bfb5bd71bba8f86d4b0cf 100644
--- a/net/http/http_proxy_client_socket_pool.cc
+++ b/net/http/http_proxy_client_socket_pool.cc
@@ -266,6 +266,11 @@ void HttpProxyClientSocketPool::CloseIdleSockets() {
   base_.CloseIdleSockets();
 }
 
+void HttpProxyClientSocketPool::CloseIdleSocketsInGroup(
+    const std::string& group_name) {
+  base_.CloseIdleSocketsInGroup(group_name);
+}
+
 int HttpProxyClientSocketPool::IdleSocketCount() const {
   return base_.idle_socket_count();
 }