[MD Bookmarks] Right click on bookmark items open context menu.

chrome/browser/resources/md_bookmarks/list.js

Index: chrome/browser/resources/md_bookmarks/list.js
diff --git a/chrome/browser/resources/md_bookmarks/list.js b/chrome/browser/resources/md_bookmarks/list.js
index 6952696a2e86c6bfd41384d541fb3a3b33d92d07..c38b6da7fa26e40059358dcc22a4fc61dd45653d 100644
--- a/chrome/browser/resources/md_bookmarks/list.js
+++ b/chrome/browser/resources/md_bookmarks/list.js
@@ -54,7 +54,14 @@ Polymer({
     this.menuItem_ = e.detail.item;
     var menu = /** @type {!CrActionMenuElement} */ (
         this.$.dropdown);
-    menu.showAt(/** @type {!Element} */ (e.detail.target));
+    if (e.detail.targetElement) {
+      menu.showAt(/** @type {!Element} */ (e.detail.targetElement));
+    } else {
+      menu.showAtPosition({
+        top: e.detail.y,
+        left: e.detail.x,
+      });
+    }
   },
 
   /** @private */
@@ -87,6 +94,20 @@ Polymer({
     this.closeDropdownMenu_();
   },
 
+  /**
+   * Close the menu on mousedown so clicks can propagate to the underlying UI.
+   * This allows the user to right click the list while a context menu is
+   * showing and get another context menu.
+   * @param {Event} e
+   * @private
+   */
+  onMenuMousedown_: function(e) {
+    if (e.path[0] != this.$.dropdown)
+      return;
+
+    this.closeDropdownMenu_();
+  },
+
   /** @private */
   closeDropdownMenu_: function() {
     var menu = /** @type {!CrActionMenuElement} */ (