sync: Introduce CryptographerProvider interface

sync/test/engine/simple_cryptographer_provider.cc

+// 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.
+
+#include "sync/test/engine/simple_cryptographer_provider.h"
+
+namespace syncer {
+
+SimpleCryptographerProvider::SimpleCryptographerProvider(
+    Cryptographer* cryptographer)
+    : cryptographer_(cryptographer) {
+}
+
+SimpleCryptographerProvider::~SimpleCryptographerProvider() {
+}
+
+bool SimpleCryptographerProvider::InitScopedCryptographer(
+    ScopedCryptographer* scoped) {
+  scoped->Initialize(new SimpleScopedCryptographerImpl(cryptographer_));
+  return scoped->IsValid();
+}
+
+SimpleScopedCryptographerImpl::SimpleScopedCryptographerImpl(
+    Cryptographer* cryptographer)
+    : cryptographer_(cryptographer) {
+}
+
+SimpleScopedCryptographerImpl::~SimpleScopedCryptographerImpl() {
+}
+
+Cryptographer* SimpleScopedCryptographerImpl::Get() const {
+  return cryptographer_;
+}
+
+}  // namespace syncer