[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 19e475d0e9456f766b3aa99b219b226fa16346d2..fca7c4a62c547ed6a3c6b68417205b658cf13706 100644
--- a/chrome/browser/resources/md_bookmarks/list.js
+++ b/chrome/browser/resources/md_bookmarks/list.js
@@ -50,7 +50,14 @@ 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 */
@@ -83,6 +90,17 @@ Polymer({
     this.closeDropdownMenu_();
   },
 
+  /**
+   * @param {Event} e

[tsergeant, 2017/04/13 01:15:47]

I think you should add a small comment here to show why this is needed

[calamity, 2017/04/13 04:56:46]

Done.

+   * @private
+   */
+  onMenuMousedown_: function(e) {
+    if (e.path[0] != this.$.dropdown)
+      return;
+
+    this.$.dropdown.close();
+  },
+
   /** @private */
   closeDropdownMenu_: function() {
     var menu = /** @type {!CrActionMenuElement} */ (