[DevTools] Adjust device mode rulers when using small scale.

third_party/WebKit/Source/devtools/front_end/emulation/DeviceModeView.js

 // Copyright 2015 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.VBox}
  */
 WebInspector.DeviceModeView = function()
 {
@@ skipping 530 matching lines @@
 
         var dipSize = size * zoomFactor / this._scale;
         var count = Math.ceil(dipSize / 5);
         var step = 1;
         if (this._scale < 0.8)
             step = 2;
         if (this._scale < 0.6)
             step = 4;
         if (this._scale < 0.4)
             step = 8;
+        if (this._scale < 0.2)
+            step = 16;
+        if (this._scale < 0.1)
+            step = 32;
 
         for (var i = count; i < this._count; i++) {
             if (!(i % step))
                 this._contentElement.lastChild.remove();
         }
 
         for (var i = this._count; i < count; i++) {
             if (i % step)
                 continue;
             var marker = this._contentElement.createChild("div", "device-mode-ruler-marker");
@@ skipping 21 matching lines @@
     /**
      * @param {number} size
      */
     _onMarkerClick: function(size)
     {
         this._applyCallback.call(null, size);
     },
 
     __proto__: WebInspector.VBox.prototype
 }