Remove obosolete SessionId setter/getter from PortAllocator.

webrtc/p2p/client/basicportallocator_unittest.cc

Index: webrtc/p2p/client/basicportallocator_unittest.cc
diff --git a/webrtc/p2p/client/basicportallocator_unittest.cc b/webrtc/p2p/client/basicportallocator_unittest.cc
index d430cce033a29289545f0c2cfb4de384cd973e67..93951ff80bbbc31183cb9ccf4f38a8a377f28f06 100644
--- a/webrtc/p2p/client/basicportallocator_unittest.cc
+++ b/webrtc/p2p/client/basicportallocator_unittest.cc
@@ -235,8 +235,8 @@ class BasicPortAllocatorTest : public testing::Test,
       int component,
       const std::string& ice_ufrag,
       const std::string& ice_pwd) {
-    std::unique_ptr<PortAllocatorSession> session = allocator_->CreateSession(
-        sid, content_name, component, ice_ufrag, ice_pwd);
+    std::unique_ptr<PortAllocatorSession> session =
+        allocator_->CreateSession(content_name, component, ice_ufrag, ice_pwd);
     session->SignalPortReady.connect(this,
                                      &BasicPortAllocatorTest::OnPortReady);
     session->SignalPortsPruned.connect(this,