Adds plumbing for QUIC early connection migration. No behavior change.

net/quic/test_tools/quic_test_utils.h

Index: net/quic/test_tools/quic_test_utils.h
diff --git a/net/quic/test_tools/quic_test_utils.h b/net/quic/test_tools/quic_test_utils.h
index 372fdc73f52e18e1809b452cdbc75602e32cc24a..3907cd76078c22ce55d3c6f900fe1afeb86006d1 100644
--- a/net/quic/test_tools/quic_test_utils.h
+++ b/net/quic/test_tools/quic_test_utils.h
@@ -296,6 +296,7 @@ class MockConnectionVisitor : public QuicConnectionVisitorInterface {
   MOCK_METHOD0(OnCanWrite, void());
   MOCK_METHOD1(OnCongestionWindowChange, void(QuicTime now));
   MOCK_METHOD0(OnConnectionMigration, void());
+  MOCK_METHOD0(OnPathDegrading, void());
   MOCK_CONST_METHOD0(WillingAndAbleToWrite, bool());
   MOCK_CONST_METHOD0(HasPendingHandshake, bool());
   MOCK_CONST_METHOD0(HasOpenDynamicStreams, bool());
@@ -697,6 +698,7 @@ class MockNetworkChangeVisitor
 
   MOCK_METHOD0(OnCongestionWindowChange, void());
   MOCK_METHOD0(OnRttChange, void());
+  MOCK_METHOD0(OnPathDegrading, void());
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MockNetworkChangeVisitor);