[DevTools] Add rulers to Device Mode.

third_party/WebKit/Source/devtools/front_end/emulation/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.Widget}
  * @implements {WebInspector.TargetManager.Observer}
  * @param {!WebInspector.Setting} widthSetting
  */
@@ skipping 244 matching lines @@
 
         if (markers.length !== this._lastReportedCount) {
             this._lastReportedCount = markers.length;
             this.dispatchEventToListeners(WebInspector.MediaQueryInspector.Events.CountUpdated, markers.length);
         }
 
         if (!this.isShowing())
             return;
 
         var oldChildrenCount = this.contentElement.children.length;
-        var scrollTop = this.contentElement.scrollTop;
         this.contentElement.removeChildren();
 
         var container = null;
         for (var i = 0; i < markers.length; ++i) {
             if (!i || markers[i].model.section() !== markers[i - 1].model.section())
                 container = this.contentElement.createChild("div", "media-inspector-marker-container");
             var marker = markers[i];
             var bar = this._createElementFromMediaQueryModel(marker.model);
             bar._model = marker.model;
             bar._locations = marker.locations;
             bar.classList.toggle("media-inspector-marker-inactive", !marker.active);
             container.appendChild(bar);
         }
-        this.contentElement.scrollTop = scrollTop;
     },
 
     /**
      * @return {number}
      */
     _zoomFactor: function()
     {
         return WebInspector.zoomManager.zoomFactor() / this._scale;
     },
 
@@ skipping 194 matching lines @@
     },
 
     /**
      * @return {boolean}
      */
     active: function()
     {
         return this._active;
     }
 }