MD WebUI: Pull 'X selected' toolbar overlay from History into shared element

ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_selection_overlay.js

Index: ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_selection_overlay.js
diff --git a/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_selection_overlay.js b/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_selection_overlay.js
new file mode 100644
index 0000000000000000000000000000000000000000..f9f75472ac6e30dcae11817eccf0cee49bc3d8e3
--- /dev/null
+++ b/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_selection_overlay.js
@@ -0,0 +1,31 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+ * @fileoverview Element which displays the number of selected items with
+ * Cancel/Delete buttons, designed to be used as an overlay on top of
+ * <cr-toolbar>. See <history-toolbar> for an example usage.
+ */
+
+Polymer({
+  is: 'cr-toolbar-selection-overlay',
+
+  properties: {
+    deleteLabel: String,
+
+    cancelLabel: String,
+
+    selectionLabel: String,
+  },
+
+  /** @private */
+  onClearSelectionTap_: function() {
+    this.fire('clear-selected-items');
+  },
+
+  /** @private */
+  onDeleteTap_: function() {
+    this.fire('delete-selected-items');
+  },
+});