Handles selection on dblclick on any bookmark list item

"ctrl + double click" acts on the highlighted/selected bookmark list items
irrespective of on which list item the action is performed. To extend this to
clicked, unhighlighted list item, invoking mouseup event handling functionality
under doubleclick event handling before command execution. mouseup event takes
care of highlighting and unhighlighting list items.

BUG=243221

Review URL: https://codereview.chromium.org/515853002

Cr-Commit-Position: refs/heads/master@{#295021}

AUTHORS

@@ -61,6 +61,7 @@ Bem Jones-Bey <bjonesbe@adobe.com>
 Ben Karel <eschew@gmail.com>
 Benjamin Jemlich <pcgod99@gmail.com>
 Bernard Cafarelli <voyageur@gentoo.org>
+Bhanukrushana Rout <b.rout@samsung.com>
 Bobby Powers <bobbypowers@gmail.com>
 Brendan Long <self@brendanlong.com>
 Brian G. Merrell <bgmerrell@gmail.com>

ui/webui/resources/js/cr/ui/list.js

@@ -467,8 +467,16 @@ cr.define('cr.ui', function() {
       var target = /** @type {HTMLElement} */(e.target);
 
       var ancestor = this.getListItemAncestor(target);
-      if (ancestor)
-        this.activateItemAtIndex(this.getIndexOfListItem(ancestor));
+      var index = -1;
+      if (ancestor) {
+        index = this.getIndexOfListItem(ancestor);
+        this.activateItemAtIndex(index);
+      }
+
+      var sm = this.selectionModel;
+      var indexSelected = sm.getIndexSelected(index);
+      if (!indexSelected)
+        this.handlePointerDownUp_(e);
     },
 
     /**