DevTools: Make sure media query inspector is updated when it is enabled.

Source/devtools/front_end/toolbox/MediaQueryInspector.js

 // Copyright 2014 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.
 
 /**
  * @constructor
  * @extends {WebInspector.View}
  * @implements {WebInspector.TargetManager.Observer}
  */
 WebInspector.MediaQueryInspector = function()
 {
     WebInspector.View.call(this);
     this.element.classList.add("media-inspector-view", "media-inspector-view-empty");
     this.element.addEventListener("click", this._onMediaQueryClicked.bind(this), false);
     this.element.addEventListener("contextmenu", this._onContextMenu.bind(this), false);
     this.element.addEventListener("webkitAnimationEnd", this._onAnimationEnd.bind(this), false);
     this._mediaThrottler = new WebInspector.Throttler(100);
 
     this._translateZero = 0;
     this._offset = 0;
     this._scale = 1;
 
     this._rulerDecorationLayer = document.createElementWithClass("div", "fill");
     this._rulerDecorationLayer.classList.add("media-inspector-ruler-decoration");
     this._rulerDecorationLayer.addEventListener("click", this._onRulerDecorationClicked.bind(this), false);
 
     WebInspector.targetManager.observeTargets(this);
 
     WebInspector.zoomManager.addEventListener(WebInspector.ZoomManager.Events.ZoomChanged, this._renderMediaQueries.bind(this), this);
-    this._scheduleMediaQueriesUpdate();
 }
 
 /**
  * @enum {number}
  */
 WebInspector.MediaQueryInspector.Section = {
     Max: 0,
     MinMax: 1,
     Min: 2
 }
@@ skipping 105 matching lines @@
         this._scale = scale;
         this._renderMediaQueries();
     },
 
     /**
      * @param {boolean} enabled
      */
     setEnabled: function(enabled)
     {
         this._enabled = enabled;
+        this._scheduleMediaQueriesUpdate();
     },
 
     /**
      * @param {?Event} event
      */
     _onMediaQueryClicked: function(event)
     {
         var mediaQueryMarkerContainer = event.target.enclosingNodeOrSelfWithClass("media-inspector-marker-container");
         if (!mediaQueryMarkerContainer)
             return;
@@ skipping 381 matching lines @@
     },
 
     /**
      * @return {?WebInspector.CSSMediaQueryExpression}
      */
     maxWidthExpression: function()
     {
         return this._maxWidthExpression;
     }
 }