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

third_party/WebKit/Source/devtools/front_end/sdk/ServiceWorkerManager.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 33 matching lines @@
     /** @type {!Map.<string, !WebInspector.ServiceWorkerRegistration>} */
     this._registrations = new Map();
     this.enable();
     this._forceUpdateSetting = WebInspector.settings.createSetting("serviceWorkerUpdateOnReload", false);
     if (this._forceUpdateSetting.get())
         this._forceUpdateSettingChanged();
     this._forceUpdateSetting.addChangeListener(this._forceUpdateSettingChanged, this);
     WebInspector.targetManager.addModelListener(WebInspector.RuntimeModel, WebInspector.RuntimeModel.Events.ExecutionContextCreated, this._executionContextCreated, this);
 }
 
+/** @enum {symbol} */
 WebInspector.ServiceWorkerManager.Events = {
-    WorkersUpdated: "WorkersUpdated",
-    RegistrationUpdated: "RegistrationUpdated",
-    RegistrationErrorAdded: "RegistrationErrorAdded",
-    RegistrationDeleted: "RegistrationDeleted"
+    WorkersUpdated: Symbol("WorkersUpdated"),
+    RegistrationUpdated: Symbol("RegistrationUpdated"),
+    RegistrationErrorAdded: Symbol("RegistrationErrorAdded"),
+    RegistrationDeleted: Symbol("RegistrationDeleted")
 }
 
 WebInspector.ServiceWorkerManager.prototype = {
     enable: function()
     {
         if (this._enabled)
             return;
         this._enabled = true;
 
         this._agent.enable();
@@ skipping 815 matching lines @@
     {
         return this._isRedundant() && (!this.errors.length || this._deleting);
     },
 
     clearErrors: function()
     {
         this._fingerprint = Symbol("fingerprint");
         this.errors = [];
     }
 }