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

sync/internal_api/attachments/attachment_service_proxy_unittest.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/internal_api/public/attachments/attachment_service_proxy.h"
 
 #include "base/bind.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/run_loop.h"
@@ skipping 15 matching lines @@
                               public base::NonThreadSafe {
  public:
   StubAttachmentService() : call_count_(0), weak_ptr_factory_(this) {
     // DetachFromThread because we will be constructed in one thread and
     // used/destroyed in another.
     DetachFromThread();
   }
 
   ~StubAttachmentService() override {}
 
-  AttachmentStore* GetStore() override { return NULL; }
-
   void GetOrDownloadAttachments(
       const AttachmentIdList& attachment_ids,
       const GetOrDownloadCallback& callback) override {
     CalledOnValidThread();
     Increment();
     scoped_ptr<AttachmentMap> attachments(new AttachmentMap());
     base::MessageLoop::current()->PostTask(
         FROM_HERE,
         base::Bind(callback,
                    AttachmentService::GET_UNSPECIFIED_ERROR,
@@ skipping 77 matching lines @@
   scoped_ptr<base::Thread> stub_thread;
   scoped_ptr<StubAttachmentService> stub;
   scoped_ptr<AttachmentServiceProxy> proxy;
 
   AttachmentService::GetOrDownloadCallback callback_get_or_download;
 
   // number of times callback_get_or_download was invoked
   int count_callback_get_or_download;
 };
 
-TEST_F(AttachmentServiceProxyTest, GetStore) {
-  EXPECT_EQ(NULL, proxy->GetStore());
-}
-
 // Verify that each of AttachmentServiceProxy's methods are invoked on the stub.
 // Verify that the methods that take callbacks invoke passed callbacks on this
 // thread.
 TEST_F(AttachmentServiceProxyTest, MethodsAreProxied) {
   proxy->GetOrDownloadAttachments(AttachmentIdList(), callback_get_or_download);
   proxy->UploadAttachments(AttachmentIdSet());
   // Wait for the posted calls to execute in the stub thread.
   WaitForStubThread();
   EXPECT_EQ(2, stub->GetCallCount());
   // At this point the stub thread has finished executed the calls. However, the
@@ skipping 26 matching lines @@
   // Now that the wrapped object has been destroyed, call again and see that we
   // don't crash and the count remains the same.
   proxy->GetOrDownloadAttachments(AttachmentIdList(), callback_get_or_download);
   WaitForStubThread();
   WaitForStubThread();
   base::RunLoop().RunUntilIdle();
   EXPECT_EQ(1, count_callback_get_or_download);
 }
 
 }  // namespace syncer