[MD Bookmarks] Support elision of bookmark names in the bookmark toast.

chrome/browser/resources/md_bookmarks/toast_manager.js

Index: chrome/browser/resources/md_bookmarks/toast_manager.js
diff --git a/chrome/browser/resources/md_bookmarks/toast_manager.js b/chrome/browser/resources/md_bookmarks/toast_manager.js
index dabd588565432ee81d5591809c244f1465691801..c0e72fca69f5cdb3bd5bd1e69b07f2ce1f519e9b 100644
--- a/chrome/browser/resources/md_bookmarks/toast_manager.js
+++ b/chrome/browser/resources/md_bookmarks/toast_manager.js
@@ -51,9 +51,39 @@ cr.define('bookmarks', function() {
      * @param {boolean} showUndo Whether the undo button should be shown.
      */
     show: function(label, showUndo) {
-      this.open_ = true;
-      // TODO(calamity): Support collapsing of long bookmark names in label.
       this.$.content.textContent = label;
+      this.showInternal_(showUndo);
+    },
+
+    /**
+     * Shows the toast, making certain text fragments collapsible.
+     * @param {!Array<!{value: string, collapsible: boolean}>} pieces
+     * @param {boolean} showUndo Whether the undo button should be shown.
+     */
+    showForStringPieces: function(pieces, showUndo) {
+      var content = this.$.content;
+      content.textContent = '';
+      pieces.forEach(function(p) {
+        if (p.value.length == 0)
+          return;
+
+        var span = document.createElement('span');
+        span.textContent = p.value;
+        if (p.collapsible)
+          span.classList.add('collapsible');
+
+        content.appendChild(span);
+      });
+
+      this.showInternal_(showUndo);
+    },
+
+    /**
+     * @param {boolean} showUndo Whether the undo button should be shown.
+     * @private
+     */
+    showInternal_: function(showUndo) {
+      this.open_ = true;
       this.showUndo_ = showUndo;
 
       if (!this.duration)