Return false if PeerConnection::GetStats() is called on invalid tracks

webrtc/api/peerconnectioninterface_unittest.cc

Index: webrtc/api/peerconnectioninterface_unittest.cc
diff --git a/webrtc/api/peerconnectioninterface_unittest.cc b/webrtc/api/peerconnectioninterface_unittest.cc
index a4a11e1252e5720d5cc71386a43bb125c7f5cb7d..3f84c3d75feaf7e88fdbeacd5b5f81f492c5d148 100644
--- a/webrtc/api/peerconnectioninterface_unittest.cc
+++ b/webrtc/api/peerconnectioninterface_unittest.cc
@@ -1577,10 +1577,7 @@ TEST_F(PeerConnectionInterfaceTest, GetStatsForVideoTrack) {
 }
 
 // Test that we don't get statistics for an invalid track.
-// TODO(tommi): Fix this test.  DoGetStats will return true
-// for the unknown track (since GetStats is async), but no
-// data is returned for the track.
-TEST_F(PeerConnectionInterfaceTest, DISABLED_GetStatsForInvalidTrack) {
+TEST_F(PeerConnectionInterfaceTest, GetStatsForInvalidTrack) {
   InitiateCall();
   rtc::scoped_refptr<AudioTrackInterface> unknown_audio_track(
       pc_factory_->CreateAudioTrack("unknown track", NULL));