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

third_party/WebKit/Source/devtools/front_end/timeline/Layers3DView.js

 /*
  * Copyright (C) 2014 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 @@
  * @enum {string}
  */
 WebInspector.Layers3DView.OutlineType = {
     Hovered: "hovered",
     Selected: "selected"
 }
 
 /**
  * @enum {string}
  */
+/** @enum {symbol} */
 WebInspector.Layers3DView.Events = {
-    LayerSnapshotRequested: "LayerSnapshotRequested",
-    PaintProfilerRequested: "PaintProfilerRequested",
+    LayerSnapshotRequested: Symbol("LayerSnapshotRequested"),
+    PaintProfilerRequested: Symbol("PaintProfilerRequested")
 }
 
 /**
  * @enum {number}
  */
 WebInspector.Layers3DView.ChromeTexture = {
     Left: 0,
     Middle: 1,
     Right: 2
 }
@@ skipping 704 matching lines @@
 /**
  * @constructor
  * @extends {WebInspector.Object}
  */
 WebInspector.LayerTextureManager = function()
 {
     WebInspector.Object.call(this);
     this.reset();
 }
 
+/** @enum {symbol} */
 WebInspector.LayerTextureManager.Events = {
-    TextureUpdated: "TextureUpated"
+    TextureUpdated: Symbol("TextureUpated")
 }
 
 WebInspector.LayerTextureManager.prototype = {
     reset: function()
     {
         /** @type {!Object.<string, !Array.<!WebInspector.LayerTextureManager.Tile>>} */
         this._tilesByLayerId = {};
         this._scale = 0;
     },
 
@@ skipping 261 matching lines @@
  */
 WebInspector.LayerTextureManager.Tile = function(snapshot, rect, traceEvent)
 {
     this.snapshot = snapshot;
     this.rect = rect;
     this.traceEvent = traceEvent;
     this.scale = 0;
     /** @type {?WebGLTexture} */
     this.texture = null;
 }