Fix some non-const ref function argument types.

net/cert/multi_log_ct_verifier_unittest.cc

Index: net/cert/multi_log_ct_verifier_unittest.cc
diff --git a/net/cert/multi_log_ct_verifier_unittest.cc b/net/cert/multi_log_ct_verifier_unittest.cc
index aea27f971956d83d300f31c95351b4af3765217e..fa4a894e653e1ba762aa93a847cbbc79da44c149 100644
--- a/net/cert/multi_log_ct_verifier_unittest.cc
+++ b/net/cert/multi_log_ct_verifier_unittest.cc
@@ -73,7 +73,7 @@ class MultiLogCTVerifierTest : public ::testing::Test {
     ASSERT_TRUE(embedded_sct_chain_.get());
   }
 
-  bool CheckForEmbeddedSCTInNetLog(TestNetLog& net_log) {
+  bool CheckForEmbeddedSCTInNetLog(const TestNetLog& net_log) {
     TestNetLogEntry::List entries;
     net_log.GetEntries(&entries);
     if (entries.size() != 2)