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

third_party/WebKit/Source/devtools/front_end/extensions/ExtensionServer.js

 /*
  * Copyright (C) 2011 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 68 matching lines @@
     this._registerHandler(commands.UpdateButton, this._onUpdateButton.bind(this));
     this._registerHandler(commands.UpdateAuditProgress, this._onUpdateAuditProgress.bind(this));
     window.addEventListener("message", this._onWindowMessage.bind(this), false);  // Only for main window.
 
     InspectorFrontendHost.events.addEventListener(InspectorFrontendHostAPI.Events.AddExtensions, this._addExtensions, this);
     InspectorFrontendHost.events.addEventListener(InspectorFrontendHostAPI.Events.SetInspectedTabId, this._setInspectedTabId, this);
 
     this._initExtensions();
 }
 
+/** @enum {symbol} */
 WebInspector.ExtensionServer.Events = {
-    SidebarPaneAdded: "SidebarPaneAdded",
-    AuditCategoryAdded: "AuditCategoryAdded"
+    SidebarPaneAdded: Symbol("SidebarPaneAdded"),
+    AuditCategoryAdded: Symbol("AuditCategoryAdded")
 }
 
 WebInspector.ExtensionServer.prototype = {
     initializeExtensions: function()
     {
         this._initializeCommandIssued = true;
         if (this._pendingExtensionInfos) {
             this._pendingExtensionInfos.forEach(this._addExtension, this);
             delete this._pendingExtensionInfos;
         }
@@ skipping 982 matching lines @@
 /**
  * @typedef {{code: string, description: string, details: !Array.<*>}}
  */
 WebInspector.ExtensionStatus.Record;
 
 WebInspector.extensionAPI = {};
 defineCommonExtensionSymbols(WebInspector.extensionAPI);
 
 /** @type {!WebInspector.ExtensionServer} */
 WebInspector.extensionServer;