[SyncFS] Unconditionally demote remote file trackers on remote-to-local sync

chrome/browser/sync_file_system/drive_backend/metadata_database_index_interface.h

 // 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.
 
 #ifndef CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_METADATA_DATABASE_INDEX_INTERFACE_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_METADATA_DATABASE_INDEX_INTERFACE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 72 matching lines @@
 
   // Returns a FileTracker whose |dirty| is set and which isn't demoted.
   // Returns 0 if not found.
   virtual int64 PickDirtyTracker() const = 0;
 
   // Demotes a dirty tracker.
   virtual void DemoteDirtyTracker(int64 tracker_id) = 0;
 
   virtual bool HasDemotedDirtyTracker() const = 0;
 
+  // Promotes single demoted dirty tracker to a normal dirty tracker.
+  virtual void PromoteDemotedDirtyTracker(int64 tracker_id) = 0;
+
   // Promotes all demoted dirty trackers to normal dirty trackers.
-  virtual void PromoteDemotedDirtyTrackers() = 0;
+  // Returns true if any tracker was promoted.
+  virtual bool PromoteDemotedDirtyTrackers() = 0;
 
   virtual size_t CountDirtyTracker() const = 0;
   virtual size_t CountFileMetadata() const = 0;
   virtual size_t CountFileTracker() const = 0;
 
   virtual void SetSyncRootTrackerID(int64 sync_root_id) const = 0;
   virtual void SetLargestChangeID(int64 largest_change_id) const = 0;
   virtual void SetNextTrackerID(int64 next_tracker_id) const = 0;
   virtual int64 GetSyncRootTrackerID() const = 0;
   virtual int64 GetLargestChangeID() const = 0;
   virtual int64 GetNextTrackerID() const = 0;
   virtual std::vector<std::string> GetRegisteredAppIDs() const = 0;
   virtual std::vector<int64> GetAllTrackerIDs() const = 0;
   virtual std::vector<std::string> GetAllMetadataIDs() const = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MetadataDatabaseIndexInterface);
 };
 
 }  // namespace drive_backend
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_METADATA_DATABASE_INDEX_INTERFACE_H_