Fixed resizing animation for extension options.

chrome/browser/resources/extensions/extension_options_overlay.js

Index: chrome/browser/resources/extensions/extension_options_overlay.js
diff --git a/chrome/browser/resources/extensions/extension_options_overlay.js b/chrome/browser/resources/extensions/extension_options_overlay.js
index 593407387c92883cf9af1c2aded9f72705745f02..ea676c705a1137d1cf1f76affe1a41fa3f0c6299 100644
--- a/chrome/browser/resources/extensions/extension_options_overlay.js
+++ b/chrome/browser/resources/extensions/extension_options_overlay.js
@@ -106,7 +106,7 @@ cr.define('extensions', function() {
       // maxHeight, but the maxHeight does not include our header height (title
       // and close button), so we need to subtract that to get the maxHeight
       // for the extension options.
-      var maxHeight = parseInt(overlay.style.maxHeight, 10) -
+      var maxHeight = parseInt(overlayStyle.maxHeight, 10) -
                       overlayHeader.offsetHeight;
       var minWidth = parseInt(overlayStyle.minWidth, 10);
 
@@ -125,8 +125,11 @@ cr.define('extensions', function() {
        * @param {{width: number, height: number}} evt
        */
       extensionoptions.onpreferredsizechanged = function(evt) {
+        // |overlayStyle.height| includes the header height, so it needs to be
+        // subtracted to get the true old preferred height.
         var oldWidth = parseInt(overlayStyle.width, 10);
-        var oldHeight = parseInt(overlayStyle.height, 10);
+        var oldHeight =
+            parseInt(overlayStyle.height, 10) - overlayHeader.offsetHeight;
         // 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
@@ -148,9 +151,13 @@ cr.define('extensions', function() {
         if (animation)
           animation.cancel();
 
+        // The header height must be added to the (old and new) preferred
+        // heights to get the full overlay heights.
         animation = overlay.animate([
-          {width: oldWidth + 'px', height: oldHeight + 'px'},
-          {width: newWidth + 'px', height: newHeight + 'px'}
+          {width: oldWidth + 'px',
+           height: (oldHeight + overlayHeader.offsetHeight) + 'px'},
+          {width: newWidth + 'px',
+           height: (newHeight + overlayHeader.offsetHeight) + 'px'}
         ], {
           duration: animationTime,
           delay: 0