DevTools: Use JS symbols instead of strings for eligible events.

third_party/WebKit/Source/devtools/front_end/workspace/IsolatedFileSystemManager.js

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 38 matching lines @@
     InspectorFrontendHost.events.addEventListener(InspectorFrontendHostAPI.Events.IndexingWorked, this._onIndexingWorked, this);
     InspectorFrontendHost.events.addEventListener(InspectorFrontendHostAPI.Events.IndexingDone, this._onIndexingDone, this);
     InspectorFrontendHost.events.addEventListener(InspectorFrontendHostAPI.Events.SearchCompleted, this._onSearchCompleted, this);
 
     this._initExcludePatterSetting();
 }
 
 /** @typedef {!{fileSystemName: string, rootURL: string, fileSystemPath: string}} */
 WebInspector.IsolatedFileSystemManager.FileSystem;
 
+/** @enum {symbol} */
 WebInspector.IsolatedFileSystemManager.Events = {
-    FileSystemAdded: "FileSystemAdded",
-    FileSystemRemoved: "FileSystemRemoved",
-    FileSystemsLoaded: "FileSystemsLoaded",
-    FileSystemFilesChanged: "FileSystemFilesChanged",
-    ExcludedFolderAdded: "ExcludedFolderAdded",
-    ExcludedFolderRemoved: "ExcludedFolderRemoved"
+    FileSystemAdded: Symbol("FileSystemAdded"),
+    FileSystemRemoved: Symbol("FileSystemRemoved"),
+    FileSystemsLoaded: Symbol("FileSystemsLoaded"),
+    FileSystemFilesChanged: Symbol("FileSystemFilesChanged"),
+    ExcludedFolderAdded: Symbol("ExcludedFolderAdded"),
+    ExcludedFolderRemoved: Symbol("ExcludedFolderRemoved")
 }
 
 WebInspector.IsolatedFileSystemManager._lastRequestId = 0;
 
 /**
  * @param {string} fileSystemPath
  * @return {string}
  */
 WebInspector.IsolatedFileSystemManager.normalizePath = function(fileSystemPath)
 {
@@ skipping 287 matching lines @@
         InspectorFrontendHost.events.removeEventListener(InspectorFrontendHostAPI.Events.SearchCompleted, this._onSearchCompleted, this);
     },
 
     __proto__: WebInspector.Object.prototype
 }
 
 /**
  * @type {!WebInspector.IsolatedFileSystemManager}
  */
 WebInspector.isolatedFileSystemManager;