Add bookmark bar/manager actions to track drag and drop.

chrome/browser/resources/bookmark_manager/js/dnd.js

Index: chrome/browser/resources/bookmark_manager/js/dnd.js
diff --git a/chrome/browser/resources/bookmark_manager/js/dnd.js b/chrome/browser/resources/bookmark_manager/js/dnd.js
index 0f0bffde29fa865f70c32d283a48ddaa5fcbd099..9f6df62de8c58590bb04e1e62ca02619e8f5c4f6 100644
--- a/chrome/browser/resources/bookmark_manager/js/dnd.js
+++ b/chrome/browser/resources/bookmark_manager/js/dnd.js
@@ -345,6 +345,7 @@ cr.define('dnd', function() {
       chrome.bookmarkManagerPrivate.startDrag(draggedNodes.map(function(node) {
         return node.id;
       }), isFromTouch);
+      chrome.metricsPrivate.recordUserAction('BookmarkManager_StartDrag');
     }
   }
 
@@ -484,6 +485,8 @@ cr.define('dnd', function() {
       else
         chrome.bookmarkManagerPrivate.drop(dropInfo.parentId);
 
+      chrome.metricsPrivate.recordUserAction('BookmarkManager_Drop');
+
       e.preventDefault();
     }
     dropDestination = null;