DevTools: move FileSystemMapping under persistence/ module

third_party/WebKit/Source/devtools/front_end/persistence/Persistence.js

 // 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.
+
 /**
  * @unrestricted
  */
 Persistence.Persistence = class extends Common.Object {
   /**
    * @param {!Workspace.Workspace} workspace
    * @param {!Bindings.BreakpointManager} breakpointManager
-   * @param {!Workspace.FileSystemMapping} fileSystemMapping
+   * @param {!Persistence.FileSystemMapping} fileSystemMapping
    */
   constructor(workspace, breakpointManager, fileSystemMapping) {
     super();
     this._workspace = workspace;
     this._breakpointManager = breakpointManager;
     /** @type {!Map<string, number>} */
     this._filePathPrefixesToBindingCount = new Map();
 
     /** @type {!Multimap<!Workspace.UISourceCode, function()>} */
     this._subscribedBindingEventListeners = new Multimap();
 
     if (Runtime.experiments.isEnabled('persistence2')) {
       var linkDecorator = new Persistence.PersistenceUtils.LinkDecorator(this);
       Components.Linkifier.setLinkDecorator(linkDecorator);
       this._mapping =
           new Persistence.Automapping(workspace, this._validateBinding.bind(this), this._onBindingRemoved.bind(this));
     } else {
       this._mapping = new Persistence.DefaultMapping(
           workspace, fileSystemMapping, this._validateBinding.bind(this), this._onBindingRemoved.bind(this));
     }
   }
 
   /**
-   * @param {function(function(!Persistence.PersistenceBinding), function(!Persistence.PersistenceBinding)):{dispose: function()}} mappingFactory
+   * @param {function(function(!Persistence.PersistenceBinding), function(!Persistence.PersistenceBinding)):!Persistence.MappingSystem} mappingFactory
    */
   _setMappingForTest(mappingFactory) {
     this._mapping.dispose();
     this._mapping = mappingFactory(this._validateBinding.bind(this), this._onBindingRemoved.bind(this));
   }
 
   /**
    * @param {!Persistence.PersistenceBinding} binding
    */
   _validateBinding(binding) {
@@ skipping 337 matching lines @@
    * @param {boolean} exactMatch
    */
   constructor(network, fileSystem, exactMatch) {
     this.network = network;
     this.fileSystem = fileSystem;
     this.exactMatch = exactMatch;
     this._removed = false;
   }
 };
 
+/**
+ * @interface
+ */
+Persistence.MappingSystem = function() {};
+
+Persistence.MappingSystem.prototype = {
+  dispose: function() {}
+};
+
 /** @type {!Persistence.Persistence} */
 Persistence.persistence;