testserver.py listens on ephemeral ports by default.

net/test/test_server.h

Index: net/test/test_server.h
diff --git a/net/test/test_server.h b/net/test/test_server.h
index 8affc12b91ca32d138ea4f76327419aa77bee982..e0cadab15b09c85c7002ced85006ba0cd3efc075 100644
--- a/net/test/test_server.h
+++ b/net/test/test_server.h
@@ -113,7 +113,7 @@ class TestServer {
   bool Stop();
 
   const FilePath& document_root() const { return document_root_; }
-  const HostPortPair& host_port_pair() const { return host_port_pair_; }
+  const HostPortPair& host_port_pair() const;
   std::string GetScheme() const;
   bool GetAddressList(AddressList* address_list) const WARN_UNUSED_RESULT;
 
@@ -189,6 +189,9 @@ class TestServer {
 
   Type type_;
 
+  // Has the server been started?
+  bool started_;
+
   DISALLOW_COPY_AND_ASSIGN(TestServer);
 };