Fix all -Wnon-virtual-dtor warnings.
This is needed to get the GN build going for several parts
of the code tree.
BUG=webrtc:3307
NOTRY=True
R=henrika@webrtc.org, nisse@webrtc.org
Review URL: https://codereview.webrtc.org/1928653005 .
Cr-Commit-Position: refs/heads/master@{#12693}
diff --git a/webrtc/api/peerconnectionfactory_unittest.cc b/webrtc/api/peerconnectionfactory_unittest.cc
index e7859d0..833242a 100644
--- a/webrtc/api/peerconnectionfactory_unittest.cc
+++ b/webrtc/api/peerconnectionfactory_unittest.cc
@@ -64,6 +64,7 @@
class NullPeerConnectionObserver : public PeerConnectionObserver {
public:
+ virtual ~NullPeerConnectionObserver() = default;
virtual void OnMessage(const std::string& msg) {}
virtual void OnSignalingMessage(const std::string& msg) {}
virtual void OnSignalingChange(