[Sync] Refactor AttachmentStore classes. Introduce concept of referrer.

sync/api/attachments/attachment_store.cc

Index: sync/api/attachments/attachment_store.cc
diff --git a/sync/api/attachments/attachment_store.cc b/sync/api/attachments/attachment_store.cc
index 91b3f956f85593c33daa3da4441907bc6b6f7415..7cf774e93175c5172a50363869baa2449731255a 100644
--- a/sync/api/attachments/attachment_store.cc
+++ b/sync/api/attachments/attachment_store.cc
@@ -10,16 +10,53 @@
 #include "base/message_loop/message_loop.h"
 #include "base/sequenced_task_runner.h"
 #include "base/thread_task_runner_handle.h"
-#include "sync/internal_api/public/attachments/attachment_store_handle.h"
+#include "sync/internal_api/public/attachments/attachment_store_frontend.h"
 #include "sync/internal_api/public/attachments/in_memory_attachment_store.h"
 #include "sync/internal_api/public/attachments/on_disk_attachment_store.h"
 
 namespace syncer {
 
-AttachmentStore::AttachmentStore() {}
-AttachmentStore::~AttachmentStore() {}
+AttachmentStore::AttachmentStore(
+    const scoped_refptr<AttachmentStoreFrontend>& frontend,
+    AttachmentReferrer referrer)
+    : frontend_(frontend), referrer_(referrer) {
+}
+
+AttachmentStore::~AttachmentStore() {
+}
+
+void AttachmentStore::Read(const AttachmentIdList& ids,
+                           const ReadCallback& callback) {
+  frontend_->Read(ids, callback);
+}
 
-scoped_refptr<AttachmentStore> AttachmentStore::CreateInMemoryStore() {
+void AttachmentStore::Write(const AttachmentList& attachments,
+                            const WriteCallback& callback) {
+  frontend_->Write(referrer_, attachments, callback);
+}
+
+void AttachmentStore::Drop(const AttachmentIdList& ids,
+                           const DropCallback& callback) {
+  frontend_->Drop(referrer_, ids, callback);
+}
+
+void AttachmentStore::ReadMetadata(const AttachmentIdList& ids,
+                                   const ReadMetadataCallback& callback) {
+  frontend_->ReadMetadata(ids, callback);
+}
+
+void AttachmentStore::ReadAllMetadata(const ReadMetadataCallback& callback) {
+  frontend_->ReadAllMetadata(referrer_, callback);
+}
+
+scoped_ptr<AttachmentStore> AttachmentStore::CreateAttachmentStoreForSync()
+    const {
+  scoped_ptr<AttachmentStore> attachment_store(
+      new AttachmentStore(frontend_, SYNC));
+  return attachment_store.Pass();
+}
+
+scoped_ptr<AttachmentStore> AttachmentStore::CreateInMemoryStore() {
   // Both frontend and backend of attachment store will live on current thread.
   scoped_refptr<base::SingleThreadTaskRunner> runner;
   if (base::ThreadTaskRunnerHandle::IsSet()) {
@@ -32,34 +69,38 @@ scoped_refptr<AttachmentStore> AttachmentStore::CreateInMemoryStore() {
   }
   scoped_ptr<AttachmentStoreBackend> backend(
       new InMemoryAttachmentStore(runner));
-  return scoped_refptr<AttachmentStore>(
-      new AttachmentStoreHandle(backend.Pass(), runner));
+  scoped_refptr<AttachmentStoreFrontend> frontend(
+      new AttachmentStoreFrontend(backend.Pass(), runner));
+  scoped_ptr<AttachmentStore> attachment_store(
+      new AttachmentStore(frontend, MODEL_TYPE));
+  return attachment_store.Pass();
 }
 
-scoped_refptr<AttachmentStore> AttachmentStore::CreateOnDiskStore(
+scoped_ptr<AttachmentStore> AttachmentStore::CreateOnDiskStore(
     const base::FilePath& path,
     const scoped_refptr<base::SequencedTaskRunner>& backend_task_runner,
     const InitCallback& callback) {
   scoped_ptr<OnDiskAttachmentStore> backend(
       new OnDiskAttachmentStore(base::ThreadTaskRunnerHandle::Get(), path));
 
-  scoped_refptr<AttachmentStore> attachment_store =
-      new AttachmentStoreHandle(backend.Pass(), backend_task_runner);
-  attachment_store->Init(callback);
-
-  return attachment_store;
-}
-
-AttachmentStoreBackend::AttachmentStoreBackend(
-    const scoped_refptr<base::SequencedTaskRunner>& callback_task_runner)
-    : callback_task_runner_(callback_task_runner) {
-}
+  scoped_refptr<AttachmentStoreFrontend> frontend =
+      new AttachmentStoreFrontend(backend.Pass(), backend_task_runner);
+  scoped_ptr<AttachmentStore> attachment_store(
+      new AttachmentStore(frontend, MODEL_TYPE));
+  frontend->Init(callback);
 
-AttachmentStoreBackend::~AttachmentStoreBackend() {
+  return attachment_store.Pass();
 }
 
-void AttachmentStoreBackend::PostCallback(const base::Closure& callback) {
-  callback_task_runner_->PostTask(FROM_HERE, callback);
+scoped_ptr<AttachmentStore> AttachmentStore::CreateMockStoreForTest(
+    scoped_ptr<AttachmentStoreBackend> backend) {
+  scoped_refptr<base::SingleThreadTaskRunner> runner =
+      base::ThreadTaskRunnerHandle::Get();
+  scoped_refptr<AttachmentStoreFrontend> attachment_store_frontend(
+      new AttachmentStoreFrontend(backend.Pass(), runner));
+  scoped_ptr<AttachmentStore> attachment_store(
+      new AttachmentStore(attachment_store_frontend, MODEL_TYPE));
+  return attachment_store.Pass();
 }
 
 }  // namespace syncer