Hides the error bubble on scroll event

ui/login/bubble.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.
 
 /**
  * @fileoverview Bubble implementation.
  */
 
 // TODO(xiyuan): Move this into shared.
 cr.define('cr.ui', function() {
@@ skipping 43 matching lines @@
 
     // Whether to hide bubble when key is pressed.
     hideOnKeyPress_: true,
 
     /** @override */
     decorate: function() {
       this.docKeyDownHandler_ = this.handleDocKeyDown_.bind(this);
       this.selfClickHandler_ = this.handleSelfClick_.bind(this);
       this.ownerDocument.addEventListener('click',
                                           this.handleDocClick_.bind(this));
+      // Set useCapture to true because scroll event does not bubble.
+      this.ownerDocument.addEventListener('scroll',
+                                          this.handleScroll_.bind(this),
+                                          true);
       this.ownerDocument.addEventListener('keydown',
                                           this.docKeyDownHandler_);
       window.addEventListener('blur', this.handleWindowBlur_.bind(this));
       this.addEventListener('webkitTransitionEnd',
                             this.handleTransitionEnd_.bind(this));
       // Guard timer for 200ms + epsilon.
       ensureTransitionEndEvent(this, 250);
     },
 
     /**
@@ skipping 220 matching lines @@
      */
     handleTransitionEnd_: function(e) {
       if (this.classList.contains('faded')) {
         this.hidden = true;
         if (this.elementToFocusOnHide_)
           this.elementToFocusOnHide_.focus();
       }
     },
 
     /**
+     * Handler of scroll event.
+     * @private
+     */
+    handleScroll_: function(e) {
+      if (!this.hidden)
+        this.hide();
+    },
+
+    /**
      * Handler of document click event.
      * @private
      */
     handleDocClick_: function(e) {
       // Ignore clicks on anchor element.
       if (e.target == this.anchor_)
         return;
 
       if (!this.hidden)
         this.hide();
@@ skipping 38 matching lines @@
     handleWindowBlur_: function(e) {
       if (!this.hidden)
         this.hide();
     }
   };
 
   return {
     Bubble: Bubble
   };
 });