[Sync] Introduce AttachmentStoreForSync class

sync/internal_api/attachments/attachment_store_test_template.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_INTERNAL_API_ATTACHMENTS_ATTACHMENT_STORE_TEST_TEMPLATE_H_
 #define SYNC_INTERNAL_API_ATTACHMENTS_ATTACHMENT_STORE_TEST_TEMPLATE_H_
 
 #include "sync/api/attachments/attachment_store.h"
 
 #include "base/bind.h"
@@ skipping 110 matching lines @@
       scoped_ptr<AttachmentMetadataList>* destination_metadata,
       const AttachmentStore::Result& source_result,
       scoped_ptr<AttachmentMetadataList> source_metadata) {
     CopyResult(destination_result, source_result);
     *destination_metadata = source_metadata.Pass();
   }
 };
 
 TYPED_TEST_CASE_P(AttachmentStoreTest);
 
+// Verify that CreateAttachmentStoreForSync() creates valid object.
+TYPED_TEST_P(AttachmentStoreTest, CreateAttachmentStoreForSync) {
+  scoped_ptr<AttachmentStoreForSync> attachment_store_for_sync =
+      this->store->CreateAttachmentStoreForSync();
+  EXPECT_NE(nullptr, attachment_store_for_sync);
+}
+
 // Verify that we do not overwrite existing attachments and that we do not treat
 // it as an error.
 TYPED_TEST_P(AttachmentStoreTest, Write_NoOverwriteNoError) {
   // Create two attachments with the same id but different data.
   Attachment attachment1 = Attachment::Create(this->some_data1);
   Attachment attachment2 =
       Attachment::CreateFromParts(attachment1.GetId(), this->some_data2);
 
   // Write the first one.
   AttachmentList some_attachments;
@@ skipping 238 matching lines @@
   const AttachmentMetadataList::const_iterator end =
       this->attachment_metadata->end();
   for (; iter != end; ++iter) {
     EXPECT_THAT(ids, testing::Contains(iter->GetId()));
     ids.erase(iter->GetId());
   }
   EXPECT_TRUE(ids.empty());
 }
 
 REGISTER_TYPED_TEST_CASE_P(AttachmentStoreTest,
+                           CreateAttachmentStoreForSync,
                            Write_NoOverwriteNoError,
                            Write_RoundTrip,
                            Read_OneNotFound,
                            Drop_DropTwoButOnlyOneExists,
                            Drop_DoesNotExist,
                            ReadMetadata,
                            ReadAllMetadata);
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_ATTACHMENTS_ATTACHMENT_STORE_TEST_TEMPLATE_H_