Make NSSCertDatabase::ListCerts work async on a worker thread.

net/cert/nss_database_filter.h

+// Copyright 2014 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.
+
+#ifndef NET_CERT_NSS_DATABASE_FILTER_H_
+#define NET_CERT_NSS_DATABASE_FILTER_H_
+
+#include "base/memory/ref_counted.h"
+#include "crypto/scoped_nss_types.h"
+#include "net/base/crypto_module.h"
+#include "net/base/net_export.h"
+
+namespace net {
+
+class X509Certificate;
+
+class NET_EXPORT NSSDatabaseFilter
+    : public base::RefCountedThreadSafe<NSSDatabaseFilter> {
+ public:
+  class CertNotAllowedPredicate {
+   public:
+    explicit CertNotAllowedPredicate(
+        const scoped_refptr<NSSDatabaseFilter>& filter);
+    bool operator()(const scoped_refptr<X509Certificate>& cert) const;
+
+   private:
+    scoped_refptr<NSSDatabaseFilter> filter_;
+  };
+
+  class ModuleNotAllowedPredicate {
+   public:
+    explicit ModuleNotAllowedPredicate(
+        const scoped_refptr<NSSDatabaseFilter>& filter);
+    bool operator()(const scoped_refptr<CryptoModule>& module) const;
+
+   private:
+    scoped_refptr<NSSDatabaseFilter> filter_;
+  };
+
+  NSSDatabaseFilter();
+
+  virtual bool IsModuleAllowed(CryptoModule::OSModuleHandle slot) const = 0;
+  virtual bool IsCertAllowed(
+      const scoped_refptr<X509Certificate>& cert) const = 0;
+
+ protected:
+  virtual ~NSSDatabaseFilter();
+
+ private:
+  friend class base::RefCountedThreadSafe<NSSDatabaseFilter>;
+
+  DISALLOW_COPY_AND_ASSIGN(NSSDatabaseFilter);
+};
+
+}  // namespace net
+
+#endif  // NET_CERT_NSS_DATABASE_FILTER_H_