[SyncFS] Delete old MetadataDatabase code

chrome/browser/sync_file_system/drive_backend/metadata_database.proto

 // 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.
 //
 // Protocol buffer definitions for Drive backend of Syncable FileSystem.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
 package sync_file_system.drive_backend;
 
 enum FileKind {
   KIND_UNSUPPORTED = 0;
   KIND_FILE = 1;
   KIND_FOLDER = 2;
 }
 
 message ServiceMetadata {
   optional int64 largest_change_id = 1;
   optional string sync_root_folder_id = 2;
 }
-
-message DriveFileMetadata {
-  // File ID of the remote file/folder which the DriveFileMetadata tracks.
-  required string file_id = 1;
-  required string parent_folder_id = 2;
-
-  optional string app_id = 3;
-  optional bool is_app_root = 4;
-
-  // Holds details of file/folder metadata.
-  message Details {
-    repeated string parent_folder_id = 1;
-    optional string title = 2;
-    optional FileKind kind = 3;
-    optional string md5 = 4;
-    optional string etag = 5;
-
-    // Creation time and modification time of the resource.
-    // Serialized by Time::ToInternalValue.
-    optional int64 creation_time = 6;
-    optional int64 modification_time = 7;
-
-    optional bool deleted = 8;
-    optional int64 change_id = 9;
-  }
-
-  // |synced_details| holds the file details snapshot when the file was
-  // fetched through remote-to-local update.
-  // This should contain same value as remote_details if |dirty| is false.
-  optional Details synced_details = 5;
-
-  // |remote_details| holds the latest file details that may not yet be
-  // applied to local metadata.
-  // This should be updated by each listed ChangeResource.
-  optional Details remote_details = 6;
-
-  // True if the file is changed since the last update for this file.
-  optional bool dirty = 7;
-
-  // True if the DriveFileMetadata is active.
-  // Remote file content update should only be applied for active
-  // DriveFileMetadata.
-  // Active DriveFileMetadata must have a unique title under its parent.
-  optional bool active = 8;
-
-  // Valid only for folders.
-  // True indicates the folder contents has not yet been fetched.
-  optional bool needs_folder_listing = 9;
-}