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..2ed6715c2fbdefa7f59c98d40a7b2b9e6da70df5 100644
--- a/chrome/browser/resources/extensions/extension_options_overlay.js
+++ b/chrome/browser/resources/extensions/extension_options_overlay.js
@@ -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.

[not at google - send to devlin, 2015/03/18 15:35:20]

And I wonder if this should use the width/height of overlayGuest rather than the
width/height of the overlay (where the width is the same of course)?

[paulmeyer, 2015/03/18 17:37:48]

I think the reason that overlayGuest isn't used here is because its width and
height are undefined the first time this handler is called. Do you still think
its worth using them instead here (and initialize them as 0/0 somewhere else
ahead of time)?

[not at google - send to devlin, 2015/03/18 19:52:06]

Ah, that could be it.

Once again rendering these offscreen then detach/attaching them to render at the
initial correct height would solve this, but well outside the scope of this
change.

Actually - what do they start off as in this case? Is it 0,0?

Btw can we rename these to oldGuestWidth and oldGuestHeight?

[paulmeyer, 2015/03/18 21:41:46]

Yes, 0,0.

I agree, those names are more meaningful.

Done.

         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