Remove the deprecated NSSCertDatabase::GetInstance() .

chrome/browser/net/nss_context_linux.cc

 // Copyright (c) 2013 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 "chrome/browser/net/nss_context.h"
 
 #include "content/public/browser/browser_thread.h"
 #include "crypto/nss_util_internal.h"
 #include "net/cert/nss_cert_database.h"
 
+namespace {
+net::NSSCertDatabase* g_nss_cert_database = NULL;
+}  // namespace
+
 crypto::ScopedPK11Slot GetPublicNSSKeySlotForResourceContext(
     content::ResourceContext* context) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
   return crypto::ScopedPK11Slot(crypto::GetPersistentNSSKeySlot());
 }
 
 crypto::ScopedPK11Slot GetPrivateNSSKeySlotForResourceContext(
     content::ResourceContext* context,
     const base::Callback<void(crypto::ScopedPK11Slot)>& callback) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
   return crypto::ScopedPK11Slot(crypto::GetPersistentNSSKeySlot());
 }
 
 net::NSSCertDatabase* GetNSSCertDatabaseForResourceContext(
     content::ResourceContext* context,
     const base::Callback<void(net::NSSCertDatabase*)>& callback) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
-  return net::NSSCertDatabase::GetInstance();
+  if (!g_nss_cert_database) {
+    g_nss_cert_database = new net::NSSCertDatabase(
+        crypto::ScopedPK11Slot(crypto::GetPersistentNSSKeySlot()));
+  }
+  return g_nss_cert_database;

[Ryan Sleevi, 2014/07/22 01:18:32]

The only reason this is safe is because of the DCHECK. If it wasn't, this could
be a double-write security bug.

Promote the DCHECK to a CHECK? Or make it use a LazyInstance<T>::Leaky, which
uses atomics for true thread-safety.

[pneubeck (no reviews), 2014/07/22 08:23:56]

The DCHECK indicates that we already don't handle access from other threads
correctly.
To be on the safe side promoting to CHECK.
Added a code, that nobody is removing the CHECK by mistake.

 }