Add TRACE_EVENT macros to net.

net/dns/host_cache.cc

 // Copyright (c) 2012 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/dns/host_cache.h"
 
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/trace_event/trace_event.h"
 #include "net/base/net_errors.h"
 
 namespace net {
 
 //-----------------------------------------------------------------------------
 
 HostCache::Entry::Entry(int error, const AddressList& addrlist,
                         base::TimeDelta ttl)
     : error(error),
       addrlist(addrlist),
@@ skipping 25 matching lines @@
   if (caching_is_disabled())
     return NULL;
 
   return entries_.Get(key, now);
 }
 
 void HostCache::Set(const Key& key,
                     const Entry& entry,
                     base::TimeTicks now,
                     base::TimeDelta ttl) {
+  TRACE_EVENT0("net", "HostCache::Set");
   DCHECK(CalledOnValidThread());
   if (caching_is_disabled())
     return;
 
   entries_.Put(key, entry, now, now + ttl);
 }
 
 void HostCache::clear() {
   DCHECK(CalledOnValidThread());
   entries_.Clear();
@@ skipping 47 matching lines @@
   if (expiration > now) {
     UMA_HISTOGRAM_CUSTOM_TIMES("DNS.CacheEvicted", expiration - now,
         base::TimeDelta::FromSeconds(1), base::TimeDelta::FromDays(1), 100);
   } else {
     UMA_HISTOGRAM_CUSTOM_TIMES("DNS.CacheExpired", now - expiration,
         base::TimeDelta::FromSeconds(1), base::TimeDelta::FromDays(1), 100);
   }
 }
 
 }  // namespace net