Close idle H2 sockets when SpdySession is initialized.

net/http/http_network_transaction_unittest.cc

Index: net/http/http_network_transaction_unittest.cc
diff --git a/net/http/http_network_transaction_unittest.cc b/net/http/http_network_transaction_unittest.cc
index c7a93f09db40de5817ebd00565cffbb982d97dba..178ad60529e02259c68b37733fec80e05b252d82 100644
--- a/net/http/http_network_transaction_unittest.cc
+++ b/net/http/http_network_transaction_unittest.cc
@@ -684,6 +684,7 @@ class CaptureGroupNameSocketPool : public ParentPool {
                      std::unique_ptr<StreamSocket> socket,
                      int id) override {}
   void CloseIdleSockets() override {}
+  void CloseIdleSocketsInGroup(const std::string& group_name) override {}
   int IdleSocketCount() const override { return 0; }
   int IdleSocketCountInGroup(const std::string& group_name) const override {
     return 0;