Don't crash if STUN error message is missing ERROR-CODE attribute.

webrtc/p2p/base/stun_unittest.cc

Index: webrtc/p2p/base/stun_unittest.cc
diff --git a/webrtc/p2p/base/stun_unittest.cc b/webrtc/p2p/base/stun_unittest.cc
index efc11b240874f137918945baebcf84cdf72d916a..15d4648f276f4483b33f398063138c16267c401c 100644
--- a/webrtc/p2p/base/stun_unittest.cc
+++ b/webrtc/p2p/base/stun_unittest.cc
@@ -1016,6 +1016,15 @@ TEST_F(StunTest, ReadErrorCodeAttribute) {
   EXPECT_EQ(kTestErrorNumber, errorcode->number());
   EXPECT_EQ(kTestErrorReason, errorcode->reason());
   EXPECT_EQ(kTestErrorCode, errorcode->code());
+  EXPECT_EQ(kTestErrorCode, msg.GetErrorCodeValue());
+}
+
+// Test that GetErrorCodeValue returns STUN_ERROR_GLOBAL_FAILURE if the message
+// in question doesn't have an error code attribute, rather than crashing.
+TEST_F(StunTest, GetErrorCodeValueWithNoErrorAttribute) {
+  StunMessage msg;
+  ReadStunMessage(&msg, kStunMessageWithIPv6MappedAddress);
+  EXPECT_EQ(STUN_ERROR_GLOBAL_FAILURE, msg.GetErrorCodeValue());
 }
 
 TEST_F(StunTest, ReadMessageWithAUInt16ListAttribute) {