Fixed the bug that caused extension options not to fit their overlays properly when zoomed.

chrome/browser/resources/extensions/extension_options_overlay.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.
 
 cr.define('extensions', function() {
   'use strict';
 
   /**
    * The ExtensionOptionsOverlay will show an extension's options page using
    * an <extensionoptions> element.
@@ skipping 109 matching lines @@
       // undesirable effects.
       var animation = null;
 
       /**
        * Resize the overlay if the <extensionoptions> changes preferred size.
        * @param {{width: number, height: number}} evt
        */
       extensionoptions.onpreferredsizechanged = function(evt) {
         var oldWidth = parseInt(overlayStyle.width, 10);
         var oldHeight = parseInt(overlayStyle.height, 10);
-        var newWidth = Math.max(evt.width, minWidth);
-        var newHeight = Math.min(evt.height, maxHeight);
+        // The overlay must be slightly larger than the extension options to
+        // avoid creating scrollbars.
+        // TODO(paulmeyer): This shouldn't be necessary, but the preferred size
+        // (coming from Blink) seems to be too small for some zoom levels. The
+        // 2-pixel addition should be removed once this problem is investigated
+        // and corrected.
+        var newWidth = Math.max(evt.width + 2, minWidth);
+        var newHeight = Math.min(evt.height + 2, maxHeight);
 
         // animationTime is the amount of time in ms that will be used to resize
         // the overlay. It is calculated by multiplying the pythagorean distance
         // between old and the new size (in px) with a constant speed of
         // 0.25 ms/px.
         var loading = document.documentElement.classList.contains('loading');
         var animationTime = loading ? 0 :
             0.25 * Math.sqrt(Math.pow(newWidth - oldWidth, 2) +
                              Math.pow(newHeight - oldHeight, 2));
 
@@ skipping 51 matching lines @@
           /** @type {HTMLDivElement} */($('extension-options-overlay')) :
           null);
     }
   };
 
   // Export
   return {
     ExtensionOptionsOverlay: ExtensionOptionsOverlay
   };
 });