Certificate Transparency: Fix Pilot log ID comparison.

net/cert/sth_distributor.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/cert/sth_distributor.h"
 
 #include "base/metrics/histogram_macros.h"
 #include "base/time/time.h"
 #include "net/cert/signed_tree_head.h"
 
 namespace {
 const char kPilotLogID[33] =
     "\xa4\xb9\x09\x90\xb4\x18\x58\x14\x87\xbb\x13\xa2\xcc\x67\x70\x0a\x3c\x35"
     "\x98\x04\xf9\x1b\xdf\xb8\xe3\x77\xcd\x0e\xc8\x0d\xdc\x10";
 }
 
 namespace net {
 
 namespace ct {
 
 STHDistributor::STHDistributor()
     : observer_list_(base::ObserverList<STHObserver>::NOTIFY_EXISTING_ONLY) {}
 
 STHDistributor::~STHDistributor() {}
 
 void STHDistributor::NewSTHObserved(const SignedTreeHead& sth) {
   FOR_EACH_OBSERVER(STHObserver, observer_list_, NewSTHObserved(sth));
 
   if (sth.log_id.compare(0, sth.log_id.size(), kPilotLogID,
-                         arraysize(kPilotLogID)) != 0)
+                         arraysize(kPilotLogID) - 1) != 0)
     return;
 
   const base::TimeDelta sth_age = base::Time::Now() - sth.timestamp;
   UMA_HISTOGRAM_CUSTOM_TIMES("Net.CertificateTransparency.PilotSTHAge", sth_age,
                              base::TimeDelta::FromHours(1),
                              base::TimeDelta::FromDays(4), 100);
 }
 
 void STHDistributor::RegisterObserver(STHObserver* observer) {
   observer_list_.AddObserver(observer);
 }
 
 void STHDistributor::UnregisterObserver(STHObserver* observer) {
   observer_list_.RemoveObserver(observer);
 }
 
 }  // namespace ct
 
 }  // namespace net