[SyncFS] Improve debug logs of MetadataDatabaseIndex

chrome/browser/sync_file_system/drive_backend/sync_engine.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/sync_engine.h"
 
 #include "base/bind.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/values.h"
 #include "chrome/browser/drive/drive_api_service.h"
@@ skipping 282 matching lines @@
 
 void SyncEngine::DownloadRemoteVersion(
     const fileapi::FileSystemURL& url,
     const std::string& version_id,
     const DownloadVersionCallback& callback) {
   // TODO(tzik): Implement this before we support manual conflict resolution.
   callback.Run(SYNC_STATUS_FAILED, webkit_blob::ScopedFile());
 }
 
 void SyncEngine::PromoteDemotedChanges() {
-  if (metadata_database_)
+  if (metadata_database_ && metadata_database_->HasLowPriorityDirtyTracker()) {
     metadata_database_->PromoteLowerPriorityTrackersToNormal();
+    FOR_EACH_OBSERVER(
+        Observer,
+        service_observers_,
+        OnRemoteChangeQueueUpdated(
+            metadata_database_->CountDirtyTracker()));
+  }
 }
 
 void SyncEngine::ApplyLocalChange(
     const FileChange& local_change,
     const base::FilePath& local_path,
     const SyncFileMetadata& local_metadata,
     const fileapi::FileSystemURL& url,
     const SyncStatusCallback& callback) {
   LocalToRemoteSyncer* syncer = new LocalToRemoteSyncer(
       this, local_metadata, local_change, local_path, url);
@@ skipping 403 matching lines @@
         tracker.tracker_kind() == TRACKER_KIND_APP_ROOT;
     if (is_app_enabled && !is_app_root_tracker_enabled)
       EnableOrigin(origin, base::Bind(&EmptyStatusCallback));
     else if (!is_app_enabled && is_app_root_tracker_enabled)
       DisableOrigin(origin, base::Bind(&EmptyStatusCallback));
   }
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system