Add default case to test method.

net/tools/quic/stateless_rejector_test.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/tools/quic/stateless_rejector.h"
 
 #include <memory>
 #include <vector>
 
 #include "base/strings/stringprintf.h"
@@ skipping 21 matching lines @@
 const char* FlagsModeToString(FlagsMode mode) {
   switch (mode) {
     case ENABLED:
       return "ENABLED";
     case STATELESS_DISABLED:
       return "STATELESS_DISABLED";
     case CHEAP_DISABLED:
       return "CHEAP_DISABLED";
     case BOTH_DISABLED:
       return "BOTH_DISABLED";
+    default:
+      DLOG(FATAL) << "Unexpected FlagsMode";
+      return nullptr;
   }
 }
 
 // Test various combinations of QUIC version and flag state.
 struct TestParams {
   QuicVersion version;
   FlagsMode flags;
 };
 
 string TestParamToString(const testing::TestParamInfo<TestParams>& params) {
@@ skipping 198 matching lines @@
   if (GetParam().flags != ENABLED || GetParam().version <= QUIC_VERSION_32) {
     EXPECT_EQ(StatelessRejector::UNSUPPORTED, rejector_.state());
     return;
   }
   EXPECT_EQ(StatelessRejector::ACCEPTED, rejector_.state());
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace net