sync: Introduce CryptographerProvider interface

sync/test/engine/simple_cryptographer_provider.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 SYNC_TEST_ENGINE_SIMPLE_CRYPTOGRAPHER_PROVIDER_H_
+#define SYNC_TEST_ENGINE_SIMPLE_CRYPTOGRAPHER_PROVIDER_H_
+
+#include "sync/engine/cryptographer_provider.h"
+
+#include "sync/util/cryptographer.h"
+
+namespace syncer {
+
+// A trivial cryptographer provider.  Exposes the given Cryptographer through
+// the CryptographerProvider interface.  Does not take ownership of the
+// |cryptographer|.
+class SimpleCryptographerProvider : public CryptographerProvider {
+ public:
+  explicit SimpleCryptographerProvider(Cryptographer* cryptographer);
+  virtual ~SimpleCryptographerProvider();
+
+  // Implementation of CryptographerProvider.
+  virtual bool InitScopedCryptographer(ScopedCryptographer* scoped) OVERRIDE;
+
+ private:
+  Cryptographer* cryptographer_;
+};
+
+class SimpleScopedCryptographerImpl : public ScopedCryptographerImpl {
+ public:
+  explicit SimpleScopedCryptographerImpl(Cryptographer* cryptographer);
+  virtual ~SimpleScopedCryptographerImpl();
+
+  // Implementation of ScopedCryptographerImpl.
+  virtual Cryptographer* Get() const OVERRIDE;
+
+ private:
+  Cryptographer* cryptographer_;
+};
+
+}  // namespace syncer
+
+#endif  // SYNC_TEST_ENGINE_SIMPLE_CRYPTOGRAPHER_PROVIDER_H_