[Sync] Services can now always assume processor exists.

chrome/browser/sync/test/integration/two_client_uss_sync_test.cc

 // Copyright 2016 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 "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chrome/browser/sync/chrome_sync_client.h"
 #include "chrome/browser/sync/profile_sync_service_factory.h"
 #include "chrome/browser/sync/test/integration/profile_sync_service_harness.h"
@@ skipping 39 matching lines @@
 
 // A FakeModelTypeService that supports observing ApplySyncChanges.
 class TestModelTypeService : public FakeModelTypeService {
  public:
   class Observer {
    public:
     virtual void OnApplySyncChanges() = 0;
   };
 
   TestModelTypeService()
-      : FakeModelTypeService(base::Bind(&ModelTypeChangeProcessor::Create)) {}
+      : FakeModelTypeService(base::Bind(&ModelTypeChangeProcessor::Create)) {
+    change_processor()->OnMetadataLoaded(syncer::SyncError(),
+                                         db().CreateMetadataBatch());
+  }
 
   syncer::SyncError ApplySyncChanges(
       std::unique_ptr<syncer::MetadataChangeList> metadata_changes,
       syncer::EntityChangeList entity_changes) override {
     syncer::SyncError error = FakeModelTypeService::ApplySyncChanges(
         std::move(metadata_changes), entity_changes);
     NotifyObservers();
     return error;
   }
 
-  void OnChangeProcessorSet() override {
-    change_processor()->OnMetadataLoaded(syncer::SyncError(),
-                                         db().CreateMetadataBatch());
-  }
-
   void AddObserver(Observer* observer) { observers_.insert(observer); }
   void RemoveObserver(Observer* observer) { observers_.erase(observer); }
 
  private:
   void NotifyObservers() {
     for (Observer* observer : observers_) {
       observer->OnApplySyncChanges();
     }
   }
 
@@ skipping 234 matching lines @@
   model2->SetServiceError(syncer::SyncError::DATATYPE_ERROR);
   // Write an item on model 1 to trigger a GetUpdates in model 2.
   model1->WriteItem(kKey1, kValue2);
 
   // The type should stop syncing but keep tracking metadata.
   ASSERT_TRUE(PrefsNotRunningChecker(GetSyncService(1)).Wait());
   ASSERT_EQ(1U, model2->db().metadata_count());
   model2->WriteItem(kKey2, kValue2);
   ASSERT_EQ(2U, model2->db().metadata_count());
 }