Add traces to HttpCache::Transaction to make it easier to follow URLRequests

net/cert/x509_certificate.cc

Index: net/cert/x509_certificate.cc
diff --git a/net/cert/x509_certificate.cc b/net/cert/x509_certificate.cc
index 7f23e7bf1d4d12b5447b576e1135f4ca7c8134f1..0d6fe95f1341bb2ea178b176304acd2fc2a6569b 100644
--- a/net/cert/x509_certificate.cc
+++ b/net/cert/x509_certificate.cc
@@ -25,6 +25,7 @@
 #include "base/strings/string_util.h"
 #include "base/synchronization/lock.h"
 #include "base/time/time.h"
+#include "base/trace_event/trace_event.h"
 #include "crypto/secure_hash.h"
 #include "net/base/registry_controlled_domains/registry_controlled_domain.h"
 #include "net/base/url_util.h"
@@ -235,6 +236,8 @@ scoped_refptr<X509Certificate> X509Certificate::CreateFromHandle(
 // static
 scoped_refptr<X509Certificate> X509Certificate::CreateFromDERCertChain(
     const std::vector<base::StringPiece>& der_certs) {
+  TRACE_EVENT0("io", "X509Certificate::CreateFromDERCertChain");
+
   // TODO(cbentzel): Remove ScopedTracker below once crbug.com/424386 is fixed.
   tracked_objects::ScopedTracker tracking_profile(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(