[SyncFS] Run ConflictResolver only when it is needed.

chrome/browser/sync_file_system/drive_backend/conflict_resolver.cc

 // Copyright 2013 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 "chrome/browser/sync_file_system/drive_backend/conflict_resolver.h"
 
 #include "base/callback.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "chrome/browser/drive/drive_api_util.h"
@@ skipping 71 matching lines @@
       const FileTracker& tracker = **itr;
       if (tracker.file_id() != target_file_id_) {
         non_primary_file_ids_.push_back(
             std::make_pair(tracker.file_id(), tracker.synced_details().etag()));
       }
     }
     RemoveNonPrimaryFiles(callback);
     return;
   }
 
-  callback.Run(SYNC_STATUS_NO_CHANGE_TO_SYNC);
+  callback.Run(SYNC_STATUS_NO_CONFLICT);
 }
 
 void ConflictResolver::DetachFromNonPrimaryParents(
     const SyncStatusCallback& callback) {
   DCHECK(!parents_to_remove_.empty());
 
   // TODO(tzik): Check if ETag match is available for
   // RemoteResourceFromDirectory.
   std::string parent_folder_id = parents_to_remove_.back();
   parents_to_remove_.pop_back();
@@ skipping 130 matching lines @@
   set_used_network(true);
   return sync_context_->GetDriveService();
 }
 
 MetadataDatabase* ConflictResolver::metadata_database() {
   return sync_context_->GetMetadataDatabase();
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system